[BUG] F-string with = special format fails to compile

[davfsa]

Describe the bug
The special f-string = causes the file to not compile

To Reproduce
Code to reproduce the behaviour:

foo = "bar"
print(f"{foo=}")

Error

Compiling /home/davfsa/coding/test-bots/test.py because it changed.
[1/1] Cythonizing /home/davfsa/coding/test-bots/test.py
/home/davfsa/coding/hikari/.venv/lib/python3.8/site-packages/Cython/Compiler/Main.py:344: FutureWarning: Cython directive 'language_level' not set, using '3str' for now (Py3). This has changed from earlier releases! File: /home/davfsa/coding/test-bots/test.py
  tree = Parsing.p_module(s, pxd, full_module_name)

Error compiling Cython file:
------------------------------------------------------------
...
foo = "bar"
print(f"{foo=}")              ^
------------------------------------------------------------

test.py:2:15: Expected ')', found '='
Traceback (most recent call last):
  File "/home/davfsa/coding/hikari/.venv/bin/cythonize", line 8, in <module>
    sys.exit(main())
  File "/home/davfsa/coding/hikari/.venv/lib/python3.8/site-packages/Cython/Build/Cythonize.py", line 224, in main
    cython_compile(path, options)
  File "/home/davfsa/coding/hikari/.venv/lib/python3.8/site-packages/Cython/Build/Cythonize.py", line 68, in cython_compile
    ext_modules = cythonize(
  File "/home/davfsa/coding/hikari/.venv/lib/python3.8/site-packages/Cython/Build/Dependencies.py", line 1110, in cythonize
    cythonize_one(*args)
  File "/home/davfsa/coding/hikari/.venv/lib/python3.8/site-packages/Cython/Build/Dependencies.py", line 1277, in cythonize_one
    raise CompileError(None, pyx_file)
Cython.Compiler.Errors.CompileError: /home/davfsa/coding/test-bots/test.py

Expected behavior
Should compile without warning.

Environment

• OS: Linux
• Python version 3.8.5
• Cython version 3.0a6

[da-woods]

Duplicate of #3796

[da-woods]

I think this is a known limitation currently. Fixes are obviously welcome