Test auth-backends on Python 3.11

[feanil]

This repository is a depedency of edx-platform and needs to be upgraded to Python 3.11 before
the Readwood release is cut (mid-April).

• Requirements are compiled with Python 3.8
• Tests are run on Python 3.8 and 3.11
• (Optional) Tests are also run with 3.12 and passing or 3.12 issues are ticketed.
• Classifiers in setup.py setup.cfg or pyproject.toml indicate Python 3.11 support
• A new version is release to PyPI
• A PR is merged to edx-platform to use the new version

[feanil]

This is done via #297 Need to ship it to edx-platform before we can call it done.

[feanil]

Merged to edx-platform.