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

@@            Coverage Diff            @@
##               main     #108   +/-   ##
=========================================
  Coverage     71.84%   71.84%           
  Complexity       37       37           
=========================================
  Files             1        1           
  Lines           103      103           
  Branches          8        8           
=========================================
  Hits             74       74           
  Misses           23       23           
  Partials          6        6           

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