text: Title: Add unit tests for the `__repr__` method of the RequestNode class
  Body: ## Unit Test
  
  ### Description
  
  Add unit tests for the `__repr__` method of the **RequestNode** class: https://github.com/scanapi/scanapi/blob/main/scanapi/tree/request_node.py#L57
  
  [ScanAPI Writing Tests Documentation](https://github.com/scanapi/scanapi/wiki/Writing-Tests)