Add CI workflow (#1)

Author: stackptr

.github/workflows/ci.yml

@@ -0,0 +1,21 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches: main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - uses: cachix/install-nix-action@v31
+      with:
+        github_access_token: ${{ secrets.GITHUB_TOKEN }}
+    - uses: cachix/cachix-action@v16
+      with:
+        name: stackptr
+        authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
+    - run: nix flake check
+    - run: nix build