chore: update GitHub branch references to use HEAD

[thinkingserious]

Checklist

• I acknowledge that all my contributions will be made under the project's license

[codecov]

Codecov Report

Merging #120 into main will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #120   +/-   ##
=======================================
  Coverage   95.60%   95.60%           
=======================================
  Files           2        2           
  Lines         341      341           
=======================================
  Hits          326      326           
  Misses         15       15           

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