Bump cachix/cachix-action from 13 to 14

Bumps [cachix/cachix-action](https://github.com/cachix/cachix-action) from 13 to 14.
- [Release notes](https://github.com/cachix/cachix-action/releases)
- [Commits](cachix/cachix-action@v13...v14)

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

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

Author: dependabot[bot]

Diff for: .github/workflows/nix.yml

@@ -54,7 +54,7 @@ jobs:
         extra_nix_config: |
           experimental-features = nix-command flakes
         nix_path: nixpkgs=channel:nixos-unstable
-    - uses: cachix/cachix-action@v13
+    - uses: cachix/cachix-action@v14
       with:
         name: haskell-language-server
         authToken: ${{ secrets.HLS_CACHIX_AUTH_TOKEN }}