Drop Python 3.9, remove unused docs and perf tests

[JoshKarpel]

No description provided.

[codecov]

Codecov Report

Merging #129 (9fe14eb) into main (af87178) will increase coverage by 0.0%.
The diff coverage is 100.0%.

@@          Coverage Diff          @@
##            main    #129   +/-   ##
=====================================
  Coverage   94.4%   94.4%           
=====================================
  Files         43      43           
  Lines       1426    1427    +1     
  Branches     110     110           
=====================================
+ Hits        1347    1348    +1     
  Misses        74      74           
  Partials       5       5           

Impacted Files	Coverage Δ
spiel/main.py	91.9% <ø> (-1.2%)	⬇️
tests/test_reloader.py	100.0% <ø> (ø)
spiel/deck.py	100.0% <100.0%> (+2.2%)	⬆️
spiel/example.py	96.7% <100.0%> (ø)
spiel/image.py	100.0% <100.0%> (ø)
spiel/input.py	69.8% <100.0%> (-0.7%)	⬇️
spiel/load.py	100.0% <100.0%> (ø)
spiel/options.py	100.0% <100.0%> (ø)
spiel/presentable.py	100.0% <100.0%> (ø)
spiel/repls.py	78.9% <100.0%> (ø)
... and 13 more

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