Update main Python version to 3.13

[greschd]

Currently blocked by sphinx-doc/sphinx#13178.

We could presumably fix that by upgrading to Sphinx 8.2.0, but that would require dropping Python 3.10 support on the doc build.
Alternatively, we could ignore the resulting warning.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.92%. Comparing base (e3d7bab) to head (1867e49).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #841   +/-   ##
=======================================
  Coverage   94.92%   94.92%           
=======================================
  Files         110      110           
  Lines        5770     5770           
  Branches      333      333           
=======================================
  Hits         5477     5477           
  Misses        292      292           
  Partials        1        1           

Flag	Coverage Δ
direct-launch	91.45% <ø> (ø)
minimum-deps	93.09% <ø> (ø)
python-3.10	94.14% <ø> (ø)
python-3.11	94.07% <ø> (ø)
python-3.12	94.07% <ø> (ø)
python-3.13	94.28% <ø> (ø)
server-2024R2	90.65% <ø> (ø)
server-2025R1	94.02% <ø> (ø)
server-2025R2	94.07% <ø> (ø)
server-latest	94.71% <ø> (ø)

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