add github action

Author: yuyuyureka

.github/workflows/build.yml

@@ -0,0 +1,18 @@
+name: "Build"
+on:
+  pull_request:
+  push:
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - uses: cachix/install-nix-action@v18
+      with:
+        extra_nix_config: |
+          access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
+    - uses: cachix/cachix-action@v12
+      with:
+        name: wobcom-public
+        authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
+    - run: nix build --log-format bar-with-logs -v