Drop support for EOL Python 3.9

[hugovk]

Python 3.9 reached end-of-life in October 2025:

https://devguide.python.org/versions/

This also reduces the CI from 158 to 146 jobs.

Also upgrade syntax for 3.10+ and bump GitHub Actions.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.46%. Comparing base (b857483) to head (9a14ae9).
⚠️ Report is 7 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #301   +/-   ##
=======================================
  Coverage   90.46%   90.46%           
=======================================
  Files          29       29           
  Lines        2938     2938           
  Branches      318      318           
=======================================
  Hits         2658     2658           
  Misses        206      206           
  Partials       74       74           

Flag	Coverage Δ
py310-pytest84-nodist-cover (macos/arm64)	86.01% <100.00%> (ø)
py310-pytest84-nodist-cover (ubuntu/x64)	86.31% <100.00%> (ø)
py310-pytest84-nodist-cover (windows/x64)	85.56% <100.00%> (-0.21%)	⬇️
py310-pytest84-xdist-cover (macos/arm64)	86.31% <100.00%> (ø)
py310-pytest84-xdist-cover (ubuntu/x64)	86.65% <100.00%> (-0.18%)	⬇️
py310-pytest84-xdist-cover (windows/x64)	86.07% <100.00%> (ø)
py310-pytest90-nodist-cover (macos/arm64)	85.77% <100.00%> (-0.21%)	⬇️
py310-pytest90-nodist-cover (ubuntu/x64)	86.28% <100.00%> (ø)
py310-pytest90-nodist-cover (windows/x64)	85.73% <100.00%> (ø)
py310-pytest90-xdist-cover (macos/arm64)	86.28% <100.00%> (ø)
py310-pytest90-xdist-cover (ubuntu/x64)	86.62% <100.00%> (-0.21%)	⬇️
py310-pytest90-xdist-cover (windows/x64)	86.04% <100.00%> (ø)
py311-pytest84-nodist-cover (macos/arm64)	86.01% <100.00%> (ø)
py311-pytest84-nodist-cover (ubuntu/x64)	86.35% <100.00%> (ø)
py311-pytest84-nodist-cover (windows/x64)	85.56% <100.00%> (-0.21%)	⬇️
py311-pytest84-xdist-cover (macos/arm64)	86.31% <100.00%> (ø)
py311-pytest84-xdist-cover (ubuntu/x64)	86.62% <100.00%> (-0.04%)	⬇️
py311-pytest84-xdist-cover (windows/x64)	86.07% <100.00%> (ø)
py311-pytest90-nodist-cover (macos/arm64)	85.97% <100.00%> (ø)
py311-pytest90-nodist-cover (ubuntu/x64)	86.28% <100.00%> (-0.24%)	⬇️
py311-pytest90-nodist-cover (windows/x64)	85.73% <100.00%> (ø)
py311-pytest90-xdist-cover (macos/arm64)	86.28% <100.00%> (ø)
py311-pytest90-xdist-cover (ubuntu/x64)	86.79% <100.00%> (+0.17%)	⬆️
py311-pytest90-xdist-cover (windows/x64)	86.04% <100.00%> (+0.20%)	⬆️
py312-pytest84-nodist-cover (macos/arm64)	86.01% <100.00%> (ø)
py312-pytest84-nodist-cover (ubuntu/x64)	86.31% <100.00%> (-0.24%)	⬇️
py312-pytest84-nodist-cover (windows/x64)	85.77% <100.00%> (ø)
py312-pytest84-xdist-cover (macos/arm64)	86.31% <100.00%> (ø)
py312-pytest84-xdist-cover (ubuntu/x64)	86.62% <100.00%> (-0.04%)	⬇️
py312-pytest84-xdist-cover (windows/x64)	85.87% <100.00%> (-0.21%)	⬇️
py312-pytest90-nodist-cover (macos/arm64)	85.97% <100.00%> (ø)
py312-pytest90-nodist-cover (ubuntu/x64)	86.28% <100.00%> (-0.04%)	⬇️
py312-pytest90-nodist-cover (windows/x64)	85.53% <100.00%> (-0.21%)	⬇️
py312-pytest90-xdist-cover (macos/arm64)	86.28% <100.00%> (ø)
py312-pytest90-xdist-cover (ubuntu/x64)	86.58% <100.00%> (ø)
py312-pytest90-xdist-cover (windows/x64)	86.04% <100.00%> (ø)
py313-pytest84-nodist-cover (macos/arm64)	86.01% <100.00%> (ø)
py313-pytest84-nodist-cover (ubuntu/x64)	86.31% <100.00%> (-0.21%)	⬇️
py313-pytest84-nodist-cover (windows/x64)	85.77% <100.00%> (+0.20%)	⬆️
py313-pytest84-xdist-cover (macos/arm64)	86.31% <100.00%> (ø)
py313-pytest84-xdist-cover (ubuntu/x64)	86.62% <100.00%> (-0.24%)	⬇️
py313-pytest84-xdist-cover (windows/x64)	85.87% <100.00%> (ø)
py313-pytest90-nodist-cover (macos/arm64)	85.97% <100.00%> (ø)
py313-pytest90-nodist-cover (ubuntu/x64)	86.31% <100.00%> (ø)
py313-pytest90-nodist-cover (windows/x64)	85.73% <100.00%> (ø)
py313-pytest90-xdist-cover (macos/arm64)	86.28% <100.00%> (ø)
py313-pytest90-xdist-cover (ubuntu/x64)	86.58% <100.00%> (-0.24%)	⬇️
py313-pytest90-xdist-cover (windows/x64)	86.04% <100.00%> (+0.20%)	⬆️
py314-pytest84-nodist-cover (macos/arm64)	89.13% <100.00%> (-0.21%)	⬇️
py314-pytest84-nodist-cover (ubuntu/x64)	89.81% <100.00%> (-0.04%)	⬇️
py314-pytest84-nodist-cover (windows/x64)	89.07% <100.00%> (ø)
py314-pytest84-xdist-cover (macos/arm64)	89.64% <100.00%> (ø)
py314-pytest84-xdist-cover (ubuntu/x64)	89.92% <100.00%> (-0.04%)	⬇️
py314-pytest84-xdist-cover (windows/x64)	89.37% <100.00%> (ø)
py314-pytest90-nodist-cover (macos/arm64)	89.34% <100.00%> (ø)
py314-pytest90-nodist-cover (ubuntu/x64)	89.64% <100.00%> (ø)
py314-pytest90-nodist-cover (windows/x64)	89.07% <100.00%> (ø)
py314-pytest90-xdist-cover (macos/arm64)	89.64% <100.00%> (ø)
py314-pytest90-xdist-cover (ubuntu/x64)	90.12% <100.00%> (ø)
py314-pytest90-xdist-cover (windows/x64)	89.17% <100.00%> (-0.21%)	⬇️
py39-pytest84-nodist-cover (macos/arm64)	?
py39-pytest84-nodist-cover (ubuntu/x64)	?
py39-pytest84-nodist-cover (windows/x64)	?
py39-pytest84-xdist-cover (macos/arm64)	?
py39-pytest84-xdist-cover (ubuntu/x64)	?
py39-pytest84-xdist-cover (windows/x64)	?
pypy311-pytest84-nodist-cover (macos/arm64)	85.15% <100.00%> (ø)
pypy311-pytest84-nodist-cover (ubuntu/x64)	85.46% <100.00%> (-0.04%)	⬇️
pypy311-pytest84-nodist-cover (windows/x64)	84.71% <100.00%> (-0.21%)	⬇️
pypy311-pytest84-xdist-cover (macos/arm64)	85.46% <100.00%> (ø)
pypy311-pytest84-xdist-cover (ubuntu/x64)	85.77% <100.00%> (-0.04%)	⬇️
pypy311-pytest84-xdist-cover (windows/x64)	85.02% <100.00%> (-0.21%)	⬇️
pypy311-pytest90-nodist-cover (macos/arm64)	85.15% <100.00%> (ø)
pypy311-pytest90-nodist-cover (ubuntu/x64)	85.46% <100.00%> (-0.24%)	⬇️
pypy311-pytest90-nodist-cover (windows/x64)	84.71% <100.00%> (-0.21%)	⬇️
pypy311-pytest90-xdist-cover (macos/arm64)	85.46% <100.00%> (ø)
pypy311-pytest90-xdist-cover (ubuntu/x64)	85.80% <100.00%> (ø)
pypy311-pytest90-xdist-cover (windows/x64)	85.02% <100.00%> (-0.21%)	⬇️

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