chore(deps): 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]>

.github/workflows/deadnix.yml

@@ -20,7 +20,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: cachix/install-nix-action@v24
-      - uses: cachix/cachix-action@v13
+      - uses: cachix/cachix-action@v14
         with:
           name: deadnix
       - uses: astro/deadnix-action@main