Generated unit test for `google-shopping-merchant-accounts` fails with `AttributeError: module 'google.shopping.type.types.types' has no attribute 'Weight'`

[parthea]

See build log here from PR https://github.com/googleapis/google-cloud-python/pull/12773

_ ERROR collecting tests/unit/gapic/merchant_accounts_v1beta/test_terms_of_service_service.py _
tests/unit/gapic/merchant_accounts_v1beta/test_terms_of_service_service.py:45: in <module>
    from google.shopping.merchant_accounts_v1beta.services.terms_of_service_service import (
google/shopping/merchant_accounts_v1beta/services/terms_of_service_service/__init__.py:16: in <module>
    from .async_client import TermsOfServiceServiceAsyncClient
google/shopping/merchant_accounts_v1beta/services/terms_of_service_service/async_client.py:39: in <module>
    from google.shopping.merchant_accounts_v1beta import gapic_version as package_version
google/shopping/merchant_accounts_v1beta/__init__.py:21: in <module>
    from .services.account_issue_service import (
google/shopping/merchant_accounts_v1beta/services/account_issue_service/__init__.py:16: in <module>
    from .async_client import AccountIssueServiceAsyncClient
google/shopping/merchant_accounts_v1beta/services/account_issue_service/async_client.py:46: in <module>
    from google.shopping.merchant_accounts_v1beta.services.account_issue_service import (
google/shopping/merchant_accounts_v1beta/services/account_issue_service/pagers.py:27: in <module>
    from google.shopping.merchant_accounts_v1beta.types import accountissue
google/shopping/merchant_accounts_v1beta/types/__init__.py:87: in <module>
    from .shippingsettings import (
google/shopping/merchant_accounts_v1beta/types/shippingsettings.py:1209: in <module>
    class Headers(proto.Message):
google/shopping/merchant_accounts_v1beta/types/shippingsettings.py:1260: in Headers
    message=types.Weight,
E   AttributeError: module 'google.shopping.type.types.types' has no attribute 'Weight'
_ ERROR collecting tests/unit/gapic/merchant_accounts_v1beta/test_user_service.py _
tests/unit/gapic/merchant_accounts_v1beta/test_user_service.py:46: in <module>
    from google.shopping.merchant_accounts_v1beta.services.user_service import (
google/shopping/merchant_accounts_v1beta/services/user_service/__init__.py:16: in <module>
    from .async_client import UserServiceAsyncClient
google/shopping/merchant_accounts_v1beta/services/user_service/async_client.py:39: in <module>
    from google.shopping.merchant_accounts_v1beta import gapic_version as package_version
google/shopping/merchant_accounts_v1beta/__init__.py:21: in <module>
    from .services.account_issue_service import (
google/shopping/merchant_accounts_v1beta/services/account_issue_service/__init__.py:16: in <module>
    from .async_client import AccountIssueServiceAsyncClient
google/shopping/merchant_accounts_v1beta/services/account_issue_service/async_client.py:46: in <module>
    from google.shopping.merchant_accounts_v1beta.services.account_issue_service import (
google/shopping/merchant_accounts_v1beta/services/account_issue_service/pagers.py:27: in <module>
    from google.shopping.merchant_accounts_v1beta.types import accountissue
google/shopping/merchant_accounts_v1beta/types/__init__.py:87: in <module>
    from .shippingsettings import (
google/shopping/merchant_accounts_v1beta/types/shippingsettings.py:1209: in <module>
    class Headers(proto.Message):
google/shopping/merchant_accounts_v1beta/types/shippingsettings.py:1260: in Headers
    message=types.Weight,
E   AttributeError: module 'google.shopping.type.types.types' has no attribute 'Weight'