Add flake8 to .pre-commit-config.taml

[jwodder]

Closes #35.

[codecov]

Codecov Report

Merging #39 (ef16622) into master (c8c0888) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #39   +/-   ##
=======================================
  Coverage   95.79%   95.79%           
=======================================
  Files          11       11           
  Lines         975      975           
=======================================
  Hits          934      934           
  Misses         41       41           

Flag	Coverage Δ
unittests	95.79% <ø> (ø)

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[yarikoptic]

thanks! let's check it in action