Allow protobuf 7.x

Protobuf 7.34.0 was released last week https://pypi.org/project/protobuf/7.34.0/

All [packages](https://github.com/googleapis/google-cloud-python/tree/main/packages) should be updated to allow Protobuf 7.x https://pypi.org/project/protobuf/7.34.0/

https://github.com/googleapis/google-cloud-python/issues/16001
https://github.com/googleapis/python-pubsub/pull/1586