fix: resolve issue handling protobuf responses in rest streaming (#604)

* fix: resolve issue handling protobuf responses in rest streaming

* raise ValueError if response_message_cls is not a subclass of proto.Message or google.protobuf.message.Message

* remove response_type from pytest.mark.parametrize

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* add test for ValueError in response_iterator._grab()

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Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>
2 files changed