Drop Python 3.9, support Python 3.13

[pquentin]

I used this as an opportunity to use 3.13 everywhere I could.

[prodsecmachine]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scanner	Critical	High	Medium	Low	Total (0)
✅	Licenses	0	0	0	0	0 issues
✅	Open Source Security	0	0	0	0	0 issues

💻 Catch issues earlier using the plugins for VS Code, JetBrains IDEs, Visual Studio, and Eclipse.

[miguelgrinberg]

I suggest a proper >= 3.13 version check here, because if not this conditional will have to be revised once we add support for 3.14.

[pquentin]

Thanks! Fixed in #810 (2cc7cb0c1). This allowed me to see that my code wasn't working, but we didn't see it as CI never tried to run Python 3.13 and Pandas 1.5. It does work now:

❯ nox -rs test-3.13
nox > Running session test-3.13(pandas_version='1.5.3')
nox > Re-using existing virtual environment at .nox/test-3-13-pandas_version-1-5-3.
nox > Session test-3.13(pandas_version='1.5.3') skipped: Pandas 1.5 does not support Python 3.13.
nox > Running session test-3.13(pandas_version='2.3.3')
nox > Re-using existing virtual environment at .nox/test-3-13-pandas_version-2-3-3.
nox > python -m pip install -r requirements-dev.txt 'pandas~=2.3.3'
^Cnox > Interrupted...
nox > Session test-3.13(pandas_version='2.3.3') interrupted.