Replace dry-run flag with one that actually exists

Author: iAmWillShepherd

.github/workflows/ci.yml

@@ -30,7 +30,7 @@ jobs:
         run: flutter analyze --no-pub --no-fatal-infos
 
       - name: Ensure the Dart code is formatted correctly
-        run: flutter format --set-exit-if-changed --dry-run .
+        run: flutter format -o show --set-exit-if-changed .
 
       - name: Run Flutter unit tests
         run: flutter test