chore(bigquery-storage): fix format (#17925)

fix #17924

Author: zhumin8

packages/google-cloud-bigquery-storage/tests/unit/test_reader_v1_arrow.py

@@ -27,6 +27,7 @@
     import importlib_metadata as metadata
 
 import google.api_core.exceptions
+
 from google.cloud.bigquery_storage import types
 
 from .helpers import SCALAR_BLOCKS, SCALAR_COLUMN_NAMES, SCALAR_COLUMNS