github-ci: initial commit

Author: bgamari

.github/workflows/flake-check.yml

@@ -0,0 +1,15 @@
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+jobs:
+  build:
+    name: Build Nix targets
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@v3
+      - name: Build default package
+        run: nix flake check