chore(deps): update codecov/codecov-action action to v4

Author: renovate[bot]

.github/workflows/flutter.yml

@@ -43,5 +43,5 @@ jobs:
       - name: Run tests
         run: flutter test --coverage --coverage-path=lcov.info
 
-      - uses: codecov/codecov-action@v3.1.0
+      - uses: codecov/codecov-action@v4.1.1