make build-homes use cachix nix installer

.github/workflows/build-machines-and-homes.yml

@@ -91,7 +91,11 @@ jobs:
           remove-codeql: 'true'
           remove-docker-images: 'true'
           build-mount-path: /nix
-      - uses: nixbuild/nix-quick-install-action@master
+      - name: Install Nix
+        uses: cachix/install-nix-action@v30
+        with:
+          install_url: https://releases.nixos.org/nix/nix-2.25.4/install
+          extra_nix_config: 'accept-flake-config = true'
       - name: Sync repository
         uses: actions/checkout@v4
         with: