https://github.com/marketplace/actions/install-nix
https://github.com/cachix/install-nix-action

samples
https://github.com/LGUG2Z/nixos-wsl-starter/blob/master/.github/workflows/build.yml
          - uses: cachix/install-nix-action@6a9a9e84a173d90b3ffb42c5ddaf9ea033fad011

2022
https://danth.me/posts/post/update_your_nix_flake_using_github_actions.html
2021
https://gvolpe.com/blog/nixos-binary-cache-ci/
https://thewagner.net/blog/2020/12/06/deploying-with-github-actions-and-more-nix/