Support Python 3.14; drop support for Python 3.9

[jwodder]

No description provided.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 54.82%. Comparing base (ed2ea7c) to head (6874b63).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #24   +/-   ##
=======================================
  Coverage   54.82%   54.82%           
=======================================
  Files           5        5           
  Lines         321      321           
  Branches       54       54           
=======================================
  Hits          176      176           
  Misses        145      145           

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