chore: use gapic-generator-python 1.3.1 (#24)

- [ ] Regenerate this pull request now. PiperOrigin-RevId: 472772457 Source-Link: googleapis/googleapis@855b74d Source-Link: https://github.com/googleapis/googleapis-gen/commit/b64b1e7da3e138f15ca361552ef0545e54891b4f Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiYjY0YjFlN2RhM2UxMzhmMTVjYTM2MTU1MmVmMDU0NWU1NDg5MWI0ZiJ9

Author: gcf-owl-bot[bot]

tests/unit/gapic/dataform_v1beta1/test_dataform.py

@@ -18,8 +18,8 @@
 # try/except added for compatibility with python < 3.8
 try:
  from unittest import mock
- from unittest.mock import AsyncMock
-except ImportError:
+ from unittest.mock import AsyncMock # pragma: NO COVER
+except ImportError: # pragma: NO COVER
  import mock
 
 import grpc