Use the latest flutter action in workflow

Author: matux

.github/workflows/ci.yml

@@ -18,7 +18,7 @@ jobs:
       - uses: actions/setup-java@v1
         with:
           java-version: "11.x"
-      - uses: subosito/flutter-action@4389e6cbc6cb8a4b18c628ff96ff90be0e926aa8
+      - uses: subosito/flutter-action@v2
         with:
           flutter-version: ${{ matrix.flutter_version }}
       - name: Cache Dart and Gradle packages
@@ -91,7 +91,7 @@ jobs:
 
     steps:
       - uses: actions/checkout@v4
-      - uses: subosito/flutter-action@4389e6cbc6cb8a4b18c628ff96ff90be0e926aa8
+      - uses: subosito/flutter-action@v2
         with:
           flutter-version: ${{ matrix.flutter_version }}
       - name: Cache pub packages