ci: add flutter dependency

Author: deandreamatias

.github/workflows/base.yaml

@@ -60,6 +60,10 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - uses: dart-lang/setup-dart@v1
+      - name: Flutter action
+        uses: subosito/flutter-action@v2
+        with:
+          channel: 'stable'
       - name: Publish package
         run: dart pub publish -v -f
       - name: Build changelog