Updates from futures import annotation.

Author: chalmerlowe

google/cloud/bigquery/external_config.py

@@ -18,7 +18,7 @@
    Job.configuration.query.tableDefinitions.
 """
 
-from __future__ import absolute_import
+from __future__ import absolute_import, annotations
 
 import base64
 import copy

google/cloud/bigquery/schema.py

@@ -14,6 +14,8 @@
 
 """Schemas for BigQuery tables / queries."""
 
+from __future__ import annotations
+
 import collections
 import copy
 import enum