Add auto rebuild

.github/workflows/main.yml

@@ -0,0 +1,27 @@
+name: "Rebuild system"
+
+on:
+  schedule:
+  - cron: "0 8 * * 0"
+
+jobs:
+  fetcher:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: "Install Nix ❄️"
+        uses: cachix/install-nix-action@v18
+        with:
+          extra_nix_config: |
+            substituters = https://pn.cachix.org/ https://cache.nixos.org/
+            trusted-public-keys = pn.cachix.org-1:KC0hqPVkcs7WUSv8xCkUNzrpDVKYh8TwZIqvhASvbJM= cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=
+
+      - name: Cachix
+        uses: cachix/cachix-action@v15
+        with:
+          name: pn
+
+      - name: "Build"
+        id: fetcher
+        run: nix build .#nixosConfigurations.t14