do not run macos every time

.github/workflows/check_macos.yml

@@ -0,0 +1,19 @@
+name: "Test template MacOS"
+on:
+  workflow_dispatch: # allows manual triggering
+  schedule:
+    - cron: '0 3 * * 0'
+jobs:
+  tests:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [macos-latest]
+    steps:
+    - uses: actions/checkout@v4
+    - uses: cachix/install-nix-action@v31
+      with:
+        github_access_token: ${{ secrets.GITHUB_TOKEN }}
+    - uses: DeterminateSystems/magic-nix-cache-action@main
+    - run: nix build ./templates/n
+    - run: nix flake check ./templates/n