Update cachix/install-nix-action action to v30 (#876)

| datasource  | package                   | from | to  |
| ----------- | ------------------------- | ---- | --- |
| github-tags | cachix/install-nix-action | v29  | v30 |

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/ci.yml

@@ -170,7 +170,7 @@ jobs:
         if: github.ref_type == 'tag'
 
       - name: Install Nix
-        uses: cachix/install-nix-action@9f70348d77d0422624097c4b7a75563948901306 # v29
+        uses: cachix/install-nix-action@08dcb3a5e62fa31e2da3d490afc4176ef55ecd72 # v30
         with:
           github_access_token: ${{ secrets.GITHUB_TOKEN }}
         if: github.ref_type == 'tag'