Bump cachix/install-nix-action from V27 to 28 in the actions group

Bumps the actions group with 1 update: [cachix/install-nix-action](https://github.com/cachix/install-nix-action).


Updates `cachix/install-nix-action` from V27 to 28
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Commits](cachix/install-nix-action@V27...V28)

---
updated-dependencies:
- dependency-name: cachix/install-nix-action
  dependency-type: direct:production
  dependency-group: actions
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/flake-check.yml

@@ -15,7 +15,7 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Install Nix
-        uses: cachix/install-nix-action@V27
+        uses: cachix/install-nix-action@V28
         with:
           install_url: https://nixos.org/nix/install
           extra_nix_config: |