ci: check if code is formatted

.github/workflows/ci.yml

@@ -0,0 +1,13 @@
+name: CI # Continuous Integration
+
+on:
+  pull_request:
+
+jobs:
+  fmt:
+    runs-on: ubuntu-24.04
+    steps:
+      -name: Checkout repository
+        uses: actions/checkout@v4
+      -name: Check formatting
+       run: cargo fmt --check --all