`separate_signature` black formatting is broken with griffe 0.32.0

[gotmax23]

Describe the bug
separate_signature: true black formatting is broken with griffe 0.32.0. I created a minimal reproducer in https://github.com/gotmax23/mkdocstrings-python-reproducer.

To Reproduce
Steps to reproduce the behavior:

1. git clone https://github.com/gotmax23/mkdocstrings-python-reproducer.git
2. Run nox -e "build(version='broken')" to build with the latest griffe that's broken
3. Run nox -e "build(version='functional')" to build with griffe < 0.32.0

The mkdocs page contains API docs for a single function in https://github.com/gotmax23/mkdocstrings-python-reproducer/blob/main/tester.py.

Expected behavior

A successful build with griffe 0.32.1.

Actual behavior

Traceback (most recent call last):
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/bin/mkdocs", line 8, in <module>
    sys.exit(cli())
             ^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/click/core.py", line 1157, in __call__
    return self.main(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/click/core.py", line 1078, in main
    rv = self.invoke(ctx)
         ^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/click/core.py", line 1688, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/click/core.py", line 1434, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/click/core.py", line 783, in invoke
    return __callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocs/__main__.py", line 250, in build_command
    build.build(cfg, dirty=not clean)
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocs/commands/build.py", line 308, in build
    _populate_page(file.page, config, files, dirty)
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocs/commands/build.py", line 181, in _populate_page
    page.render(config, files)
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocs/structure/pages.py", line 270, in render
    self.content = md.convert(self.markdown)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/markdown/core.py", line 264, in convert
    root = self.parser.parseDocument(self.lines).getroot()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/markdown/blockparser.py", line 90, in parseDocument
    self.parseChunk(self.root, '\n'.join(lines))
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/markdown/blockparser.py", line 105, in parseChunk
    self.parseBlocks(parent, text.split('\n\n'))
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/markdown/blockparser.py", line 123, in parseBlocks
    if processor.run(parent, blocks) is not False:
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocstrings/extension.py", line 127, in run
    html, handler, data = self._process_block(identifier, block, heading_level)
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocstrings/extension.py", line 213, in _process_block
    rendered = handler.render(data, options)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocstrings_handlers/python/handler.py", line 328, in render
    return template.render(
           ^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/jinja2/environment.py", line 1301, in render
    self.environment.handle_exception()
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/jinja2/environment.py", line 936, in handle_exception
    raise rewrite_traceback_stack(source=source)
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocstrings_handlers/python/templates/material/module.html", line 1, in top-level template code
    {% extends "_base/module.html" %}
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocstrings_handlers/python/templates/material/_base/module.html", line 55, in top-level template code
    {% block contents scoped %}
^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocstrings_handlers/python/templates/material/_base/module.html", line 62, in block 'contents'
    {% block children scoped %}
^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocstrings_handlers/python/templates/material/_base/module.html", line 66, in block 'children'
    {% include "children.html" with context %}
^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocstrings_handlers/python/templates/material/children.html", line 1, in top-level template code
    {% extends "_base/children.html" %}
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocstrings_handlers/python/templates/material/_base/children.html", line 76, in top-level template code
    {% include function|get_template with context %}
^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocstrings_handlers/python/templates/material/function.html", line 1, in top-level template code
    {% extends "_base/function.html" %}
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocstrings_handlers/python/templates/material/_base/function.html", line 45, in top-level template code
    {% block signature scoped %}
^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocstrings_handlers/python/templates/material/_base/function.html", line 47, in block 'signature'
    {% filter format_signature(function, config.line_length, crossrefs=config.signature_crossrefs) %}
^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocstrings_handlers/python/rendering.py", line 105, in do_format_signature
    signature = _format_signature(callable_path, signature, line_length)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocstrings_handlers/python/rendering.py", line 76, in _format_signature
    formatted = formatter(formatable, line_length)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gotmax/dev/repros/mkdocstrings-python/.nox/build-version-broken/lib/python3.11/site-packages/mkdocstrings_handlers/python/rendering.py", line 266, in formatter
    return format_str(code, mode=mode)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "src/black/__init__.py", line 1085, in format_str
  File "src/black/__init__.py", line 1095, in _format_str_once
  File "src/black/parsing.py", line 100, in lib2to3_parse
black.parsing.InvalidInput: Cannot parse: 1:50: def xxx(schemes: Collection[str] | None = 'http', 'ftp', 'file', 'https') -> str | None: pass

System (please complete the following information):

• mkdocstrings-python version: 1.2.0
• Python version: 3.11
• OS: Linux

[pawamoy]

Thanks for the great report, I'm investigating, and should be able to fix it before monday 😄

[gotmax23]

Thank you!