chore(deps): update codecov/codecov-action action to v3 (#22)

Co-authored-by: Renovate Bot <[email protected]>

Author: renovate[bot]

.github/workflows/flutter-test.yml

@@ -32,4 +32,4 @@ jobs:
       - name: Run tests
         run: flutter test --coverage --coverage-path=lcov.info
 
-      - uses: codecov/codecov-action@v2.1.0
+      - uses: codecov/codecov-action@v3.1.0