Fix failing CI jobs

[abravalheri]

Summary of changes

• Unify passenv with pass_env in tox.ini so we don't have trouble with TOX_OVERRIDE
• Use Python 3.11 inventory to avoid errors with distutils references

Fix fbe0d79#commitcomment-129798103

Pull Request Checklist

• Changes have tests
• News fragment added in newsfragments/.
  (See documentation for details)

[abravalheri]

This is a copy of the comment where I was keeping track of the investigation:

For some reason, this change (fbe0d79) is failing on the CI for tox -e docs and on Windows...

For the docs error, sphinx/sphinx-doc#11662 seems to be closed so we can probably remove the cap and see what happens.

For the windows error, is it possible that a newer version of the Github worker node doesn't export the windir environment variable?

UPDATE 1: For the windows error, maybe it happens because now we have a TOX_OVERRIDE: testenv.pass_env+=... env var... I think that will cause both passenv and pass_env to be present in the tox configuration and tox will prefer the later, ignoring passenv completely...

UPDATE 2: The sphinx error is probably described by sphinx-doc/sphinx#11720.

UPDATE 3: Sphinx may error even for Python 3.10, because it will fail on any warning.

UPDATE 4: Actually the sphinx errors where happening because the distutils functions are no longer part of the intersphinx inventory for Python 3.12... Changing the intersphinx_mapping to use Python 3.11 may solve the problem.

[jaraco]

This workaround is fine as a stop gap. I think the long-term strategy is for Setuptools to own the distutils documentation (https://setuptools.pypa.io/en/latest/deprecated/distutils/index.html). Probably the proper fix is to simply re-point distutils references to this documentation. I filed #4081 to track.