Update drive-app.sh

Try to fix the ci issue https://github.com/firebase/snippets-flutter/actions/runs/11157277326/job/31011251101?pr=36

Author: cynthiajoan

Diff for: .github/workflows/scripts/drive-app.sh

@@ -5,7 +5,8 @@ TARGET_PATH="packages/$PROJECT_NAME/"
 
 # The && are necessary for some reason when using the Android Emulator action
 pushd "$TARGET_PATH" || exit &&
-flutter clean &&
+flutter pub cache clean &&
+flutter channel stable &&
 flutter pub get &&
 dart format . &&
 flutter test integration_test