[SCSB-234] use Python 3.13 to build docs with Sphinx 9

[zacharyburnett]

Resolves SCSB-234

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.60%. Comparing base (7239acd) to head (d225e13).
⚠️ Report is 13 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #311      +/-   ##
==========================================
- Coverage   91.77%   89.60%   -2.17%     
==========================================
  Files          17       17              
  Lines        2552     2560       +8     
==========================================
- Hits         2342     2294      -48     
- Misses        210      266      +56     

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[schlafly]

romanisim doesn't use towncrier (or have any change log at all) at the moment, so I think this update isn't quite what we would want.

[zacharyburnett]

romanisim doesn't use towncrier (or have any change log at all) at the moment, so I think this update isn't quite what we would want.

Oh, duh! 😅 that's why there are new lines. I'll fix that