docs: change master branch to another

[peaceiris]

Build and deploy GitHub Pages from any branch beta The GitHub Blog

Repositories that use GitHub Pages can now build and deploy from any branch. Publishing to the special gh-pages branch will still work the same as it always has, but you can now choose a different branch in your repository as the publishing source. This functionality also removes the hardcoded dependency on user and organization pages having a master branch.

[codecov]

Codecov Report

Merging #436 into main will decrease coverage by 0.51%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #436      +/-   ##
==========================================
- Coverage   52.32%   51.81%   -0.52%     
==========================================
  Files           4        4              
  Lines         279      276       -3     
  Branches       50       47       -3     
==========================================
- Hits          146      143       -3     
  Misses        132      132              
  Partials        1        1              

Impacted Files	Coverage Δ
src/utils.ts	97.61% <0.00%> (-2.39%)	⬇️
src/git-utils.ts	33.82% <0.00%> (+0.24%)	⬆️

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