Mark Python 3.13 as supported too

[mtreinish]

This commit adds Python 3.13 to CI and to the trove classifiers in the package metadata to indicate that it's supported.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.48%. Comparing base (9519f4e) to head (4036a37).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #369   +/-   ##
=======================================
  Coverage   61.48%   61.48%           
=======================================
  Files          30       30           
  Lines        2617     2617           
  Branches      404      404           
=======================================
  Hits         1609     1609           
  Misses        889      889           
  Partials      119      119           

Flag	Coverage Δ
unittests	61.48% <ø> (ø)

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