Test with Python 3.11-3.13

[danyeaw]

Description

Right now we are testing on CI with version 3.7 through 3.10. I propose that we should start testing on CI with versions up to Python 3.13. We should also update the setup.cfg metadata to show that these latest versions are officially supported.

I would also be interested in feedback on how long to continue to support older versions of Python. I think most libraries drop support once a version goes end of life. Here are the End of Line Dates (no further security updates):

• Python 3.7 - 27 Jun 2023
• Python 3.8 - 07 Oct 2024

Looking at PyPI stats, and Python 3.7 makes up 40-50% of all downloads, so it seems like we should continue to support it for at least some period of time.

[danyeaw]

I just noticed that @RRosio also started a PR to fix this one here: #294