Bump subosito/flutter-action from 1 to 2.3.0

Bumps [subosito/flutter-action](https://github.com/subosito/flutter-action) from 1 to 2.3.0.
- [Release notes](https://github.com/subosito/flutter-action/releases)
- [Commits](https://github.com/subosito/flutter-action/compare/v1...v2.3.0)

---
updated-dependencies:
- dependency-name: subosito/flutter-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/dart.yml

@@ -12,7 +12,7 @@ jobs:
       - uses: actions/setup-java@v1
         with:
           java-version: '12.x'
-      - uses: subosito/flutter-action@v1
+      - uses: subosito/flutter-action@v2.3.0
       - name: Version
         run: flutter doctor -v
       - name: Install dependencies