Bump cachix/install-nix-action from 30 to 31 (#4525)

Bumps [cachix/install-nix-action](https://github.com/cachix/install-nix-action) from 30 to 31.
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Commits](cachix/install-nix-action@v30...v31)

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

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

Author: dependabot[bot]

.github/workflows/nix.yml

@@ -49,7 +49,7 @@ jobs:
     steps:
     - uses: actions/checkout@v3
 
-    - uses: cachix/install-nix-action@v30
+    - uses: cachix/install-nix-action@v31
       with:
         extra_nix_config: |
           experimental-features = nix-command flakes