Update codecov/codecov-action action to v4 (#226)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/flutter.yml

@@ -40,7 +40,7 @@ jobs:
         with:
           name: failures
           path: "**/failures/*.png"
-      - uses: codecov/codecov-action@v3
+      - uses: codecov/codecov-action@v4
 
   build_apk:
     if: ${{ github.ref == 'refs/heads/master' || contains(github.ref, 'android') }}