Provide this as a GH Action

[hoijui]

This could make sense for (at least) anyone that uses static site generators on GH Pages, as a post-processing step.
That is a huge potential clientele!

Somewhat related to #30.

[eumas42]

I have handled it the following way. Might be not the best, but does its job

- name: "Minify"
  run: |
    set -x
    CHECKSUM_EXPECTED="e848a60abfd92441fd8eca99281074c166f6a7ce8e05eea3d8033c49ea66524d"
    wget https://github.com/wilsonzlin/minify-html/releases/download/v0.15.0/minhtml-0.15.0-x86_64-unknown-linux-gnu
    
    if ! (echo "$CHECKSUM_EXPECTED minhtml-0.15.0-x86_64-unknown-linux-gnu" | sha256sum -c --status); then
      echo "File corrupt!!!"
      exit 1
    fi
    chmod u+x minhtml-0.15.0-x86_64-unknown-linux-gnu
    ./minhtml-0.15.0-x86_64-unknown-linux-gnu --keep-closing-tags --minify-css ./mysite/*.html