nix: put workflow in different file

.github/workflows/ci.yaml

@@ -44,19 +44,3 @@ jobs:
       - name: Build Hyprland with LEGACY_RENDERER
         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

.github/workflows/nix-build.yaml

@@ -0,0 +1,19 @@
+name: Build Hyprland (Nix)
+
+on: [push, pull_request, workflow_dispatch]
+jobs:
+  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