Test enmerkar-underscore 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]

Looks like this one is a bit complicated, it depends on an old version of markey which has a regex that isn't valid in Python 3.11/3.12 so we'll probably need to fork that and update this library to use a corrected version.

[mariajgrimaldi]

Here's is the latest commit made to conf/locale/babel_underscore.cfg, where this library is used -- it was the only reference I could find in edx-platform. The commit was made by @awais786 4 years ago. Do you know if this library is still used in the translation process?

[mariajgrimaldi]

I unassigned myself since @feanil is already working on fixing the issue with the unmaintained requirement. Thank you!

[feanil]

I took a quick look and it looks like we do still need this extractor because of all the underscore templates that still exist in edx-platform.