`showcase_mypy` fails with `mypy==1.11.0`

[parthea]

The showcase_mypy nox session started failing at HEAD with a recent release of mypy 1.11.0

https://pypi.org/project/mypy/1.11.0/

nox > mypy -p google
mypy.ini: [mypy]: python_version: Python 3.7 is not supported (must be 3.8 or higher)
google/showcase_v1beta1/services/messaging/async_client.py:179: error: Argument 1 to "get_transport_class" of "MessagingClientMeta" has incompatible type "type[type[MessagingClient]]"; expected "MessagingClientMeta"  [arg-type]
google/showcase_v1beta1/services/identity/async_client.py:169: error: Argument 1 to "get_transport_class" of "IdentityClientMeta" has incompatible type "type[type[IdentityClient]]"; expected "IdentityClientMeta"  [arg-type]
google/showcase_v1beta1/services/echo/async_client.py:182: error: Argument 1 to "get_transport_class" of "EchoClientMeta" has incompatible type "type[type[EchoClient]]"; expected "EchoClientMeta"  [arg-type]
Found 3 errors in 3 files (checked 37 source files)
nox > Command mypy -p google failed with exit code 1
nox > Session showcase_mypy failed.

The test passed with mypy== 1.10.1. There could potentially be a regression in mypy as mentioned in python/mypy#17566.

[daniel-sanche]

Looks like I reported a duplicate of this: #2087

Addressed this in #2088