Not compatible with Sphinx 4: AttributeError: 'Automodsumm' object has no attribute 'warn'

[JWCook]

Autosummary.warn() has been deprecated since Sphinx 2 (reference) and was removed in Sphinx 4. The self.warn() statements should be replaced with logger.warning().

Example traceback:

Exception occurred:
  File ".venv/lib/python3.8/site-packages/sphinx_automodapi/automodsumm.py", line 159, in run
    self.warn('Tried to skip objects {objs} in module {mod}, '
AttributeError: 'Automodsumm' object has no attribute 'warn'

This can be reproduced by installing Sphinx>=4.0.0 and then, for example, :skip:ing a member that doesn't exist:

.. automodsumm:: my_module
    :skip: some_nonexistent_member