refactor(gha): use cachix/install-nix-action

Signed-off-by: Sefa Eyeoglu <[email protected]>

Author: Scrumplex

.github/workflows/ci.yml

@@ -13,8 +13,9 @@ jobs:
         uses: actions/checkout@v5
         with:
           persist-credentials: false
-      - name: Install Nix
-        uses: DeterminateSystems/nix-installer-action@v19
+      - uses: cachix/install-nix-action@v31
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
       - name: Run checks
         run: |
           nix flake check --print-build-logs --show-trace