update flutter version

Author: yulingtianxia

.github/workflows/release.yml

@@ -17,7 +17,7 @@ jobs:
  - uses: subosito/flutter-action@v2
  with:
  # same with pubspec.yaml
- flutter-version: "2.8.1"
+ flutter-version: "3.0.0"
  - run: flutter pub get
  working-directory: dart_native/example
  - run: flutter analyze --no-pub --no-current-package lib/ test/