message: udpate PHP_METHOD(swoole_http_client, download).
diff: @@ -2067,7 +2067,7 @@ static PHP_METHOD(swoole_http_client, download)
  zval *download_file;
  off_t offset = 0;
  - if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "szz", &uri, &uri_len, &download_file, &finish_cb, &offset) == FAILURE)
  + if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "szz|l", &uri, &uri_len, &download_file, &finish_cb, &offset) == FAILURE)
  {
  return;
  }
  