Update flutter.yml

Author: cloudwebrtc

.github/workflows/flutter.yml

@@ -14,7 +14,7 @@ jobs:
       - uses: actions/setup-java@v1
         with:
           java-version: '12.x'
-      - uses: subosito/flutter-action@v1.1.1
+      - uses: subosito/flutter-action@v1
         with:
           flutter-version: '1.8.4'
           channel: 'beta'