Bump codecov-action to v4 with a secret token

Author: leszekhanusz

.github/workflows/tests.yml

@@ -73,4 +73,7 @@ jobs:
       - name: Test with coverage
         run: pytest --cov=gql --cov-report=xml --cov-report=term-missing tests
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
+          with:
+            fail_ci_if_error: false
+            token: ${{ secrets.CODECOV_TOKEN }}