chore(deps): update codecov/codecov-action action to v3.1.6

Author: renovate[bot]

.github/workflows/tests.yml

@@ -41,7 +41,7 @@ jobs:
       - name: Run tests
         run: flutter test --coverage --coverage-path=lcov.info
 
-      - uses: codecov/[email protected].2
+      - uses: codecov/[email protected].6
         if: ${{ matrix.channel == 'stable' }}
 
   test-old-versions: