add token check for file download operation.

mdrsclient/api/files.py

@@ -111,6 +111,7 @@ class FilesApi(BaseApi):
     def download(self, file: File, path: str) -> bool:
         # print(self.__class__.__name__ + "::" + sys._getframe().f_code.co_name)
         url = file.download_url
+        token_check(self.connection)
         response = self.connection.get(url, stream=True)
         self._raise_response_error(response)
         try: