ci: fix the deprecated argument of codecov

Author: panjf2000

.github/workflows/test.yml

@@ -89,7 +89,7 @@ jobs:
       - name: Upload code coverage report to Codecov
         uses: codecov/codecov-action@v5
         with:
-          file: ./codecov.report
+          files: ./codecov.report
           flags: unittests
           name: codecov-ants
           fail_ci_if_error: true