Update Flutter version in GitHub Action

Author: jocubeit

.github/workflows/flutter-tests.yml

@@ -13,7 +13,7 @@ jobs:
 
     env:
       FLUTTER_CHANNEL: master
-      FLUTTER_VERSION: 3.28.0-0.1.pre
+      FLUTTER_VERSION: 3.29.0
 
     steps:
       # Step 1: Checkout repository