Bump cachix/install-nix-action from 22 to 23 (#57)

Bumps [cachix/install-nix-action](https://github.com/cachix/install-nix-action) from 22 to 23.
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Commits](cachix/install-nix-action@v22...v23)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/shellspec.yml

@@ -37,7 +37,7 @@ jobs:
           fetch-depth: 0
 
       - if: ${{ matrix.os == 'ubuntu-latest' }}
-        uses: cachix/install-nix-action@v22
+        uses: cachix/install-nix-action@v23
         with:
           nix_path: nixpkgs=channel:nixos-unstable
           extra_nix_config: |