MAINT: pandas.util.testing.assertRaises removed

This method was removed in
pandas-dev/pandas#16089 in favor of
pytest.raises.

pandas_gbq/tests/test_gbq.py

@@ -9,6 +9,7 @@
 import logging
 
 import numpy as np
+import pytest
 
 from distutils.version import StrictVersion
 from pandas import compat