chore: add CI workflow

.github/workflows/ci.yml

@@ -0,0 +1,15 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  lint:
+    - uses: actions/checkout@v2
+    - uses: NTBBloodbath/selene-action@v1
+      with:
+        token: ${{ secrets.GITHUB_TOKEN }}
+        args: lua