Remove support for Python 3.8

[kajinamit]

Python 3.8 already reached its EOL on 2024-10-07 [1].

[1] https://devguide.python.org/versions/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.43%. Comparing base (10b9777) to head (581f7b8).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #376   +/-   ##
=======================================
  Coverage   61.43%   61.43%           
=======================================
  Files          30       30           
  Lines        2614     2614           
  Branches      404      404           
=======================================
  Hits         1606     1606           
  Misses        889      889           
  Partials      119      119           

Flag	Coverage Δ
unittests	61.43% <ø> (ø)

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