build(deps): bump cachix/install-nix-action from 19 to 20

Bumps [cachix/install-nix-action](https://github.com/cachix/install-nix-action) from 19 to 20.
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Commits](https://github.com/cachix/install-nix-action/compare/v19...v20

)

---
updated-dependencies:
- dependency-name: cachix/install-nix-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/prettier.yml

@@ -16,7 +16,7 @@ jobs:
               uses: actions/checkout@v3
 
             - name: Install the Nix package manager
-              uses: cachix/install-nix-action@v19
+              uses: cachix/install-nix-action@v20
 
             - name: Checks
               run: nix run nixpkgs#nodePackages.prettier -- --check .