chore: use gapic-generator-python 1.0.0 (#348)

- [ ] Regenerate this pull request now.

PiperOrigin-RevId: 451250442

Source-Link: googleapis/googleapis@cca5e81

Source-Link: googleapis/googleapis-gen@0b219da
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiMGIyMTlkYTE2MWE4YmRjYzNjNmY3YjJlZmNkODIxMDUxODJhMzBjYSJ9

packages/google-cloud-bigquery-datatransfer/tests/unit/gapic/bigquery_datatransfer_v1/test_data_transfer_service.py

@@ -13,9 +13,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-import math
 import os
 
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
+
+import math
+
 from google.api_core import gapic_v1, grpc_helpers, grpc_helpers_async, path_template
 from google.api_core import client_options
 from google.api_core import exceptions as core_exceptions
@@ -30,7 +38,6 @@
 from google.rpc import status_pb2  # type: ignore
 import grpc
 from grpc.experimental import aio
-import mock
 from proto.marshal.rules.dates import DurationRule, TimestampRule
 import pytest