Enable format check to ensure it fails

Author: jasikpark

.github/workflows/swiftfmt.yml

@@ -17,6 +17,5 @@ jobs:
         with:
           show-progress: false
 
-    # Re-enable in follow-up PR that does the formatting.
-    #   - name: Check formating
-    #     run: ./swift-format.sh check
+      - name: Check formating
+        run: ./swift-format.sh check