Merge pull request #13 from Flutter-Dart-Open-Source/renovate/actions-checkout-3.x

chore(deps): update actions/checkout action to v3

Author: hoc081098

.github/workflows/flutter.yml

@@ -20,7 +20,7 @@ jobs:
         channel: [ 'stable', 'beta' ]
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
 
       - uses: subosito/[email protected]
         with: