Add action

.github/workflows/checks.yml

@@ -0,0 +1,21 @@
+name: Checks
+
+on:
+  pull_request: {}
+  push:
+    branches:
+      - main
+
+jobs:
+  stylua:
+    name: Formatting
+    runs-on: ubuntu-latest
+    steps:
+      - name: Fetch code
+        uses: actions/checkout@v4
+      - name: Check formatting
+        uses: JohnnyMorganz/stylua-action@v4
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          version: latest
+          args: --check .