nix: added workflow

.github/workflows/ci.yaml

@@ -45,3 +45,18 @@ jobs:
         run: |
           make legacyrenderer
 
+  nix:
+    name: "Build Hyprland (Nix)"
+    runs-on: ubuntu-latest
+    steps:
+    - name: Clone repository
+      uses: actions/checkout@v3
+    - name: Install nix
+      uses: cachix/install-nix-action@v17
+      with:
+        install_url: https://releases.nixos.org/nix/nix-2.8.0/install
+        extra_nix_config: |
+          auto-optimise-store = true
+          experimental-features = nix-command flakes
+    - name: Build HyprLand with default settings
+      run: nix build --print-build-logs