CI: Add test job for Python 3.13

[EwoutH]

Python 3.13 is now in beta, thus is might be useful to start testing what works and what doesn't.

This PR adds a Python 3.13 job on Ubuntu.

Dependency tracker

• rpds (Make Python 3.13 Compatible  crate-py/rpds#79)
• watchfiles (Release wheels for Python 3.13 samuelcolvin/watchfiles#276, Bump up PyO3 to 0.22.2 samuelcolvin/watchfiles#287)
• matplotlib (Backport PR #28293 and #28668: Enable 3.13 wheels and bump cibuildwheel matplotlib/matplotlib#28688, waiting on 3.9.2 release)

[EwoutH]

Watchfiles has issued a new release that’s compatible with Python 3.13.

Now it looks like it’s stuck, the CI run times out without readable log.

Maybe try an install without uv, but with regular pip.

[rht]

Will it always be the case that uv can't be used on the pre-release Python? Or is there an unknown one-time error on uv that caused this (should be reported to them?)? The former means we have to live with the CI being as slow as the Python 3.13pre-release build.

[EwoutH]

Will it always be the case that uv can't be used on the pre-release Python?

Depends. In this case Pandas doesn't have a Python 3.13 wheel on PyPI yet. uv didn't cache Pandas, so a build takes ~4 minutes. Regular pip does cache stuff, which makes it only 30 seconds.

We could configure uv cache, but I thought it was out of scope for this PR.

We could also wait with this PR until Pandas publishes a Python 3.13 wheel.

[rht]

It's about as slow as the Windows build anyway, so it should be fine.