docs: update Google Python Style Guide

[github-actions]

This PR updates the vendored Google Python Style Guide to the latest version.

Source: https://github.com/google/styleguide/blob/gh-pages/pyguide.md

This is an automated monthly sync. Please review the changes to ensure
they don't conflict with our local overrides (e.g., 100-char line length).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (6dddd42) to head (5527429).

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #160   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            9         9           
  Lines         1133      1133           
  Branches       134       134           
=========================================
  Hits          1133      1133           

Flag	Coverage Δ
unittests	100.00% <0.00%> (ø)

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[github-actions]

🐳 Docker image built and pushed: ghcr.io/dannysauer/stampbot:pr-91eedd9