[stubsabot] Bump protobuf to ~=6.33.2

[github-actions[bot]]

Release: https://pypi.org/pypi/protobuf/6.33.2 Homepage: https://developers.google.com/protocol-buffers/ Repository: https://github.com/protocolbuffers/protobuf Typeshed stubs: https://github.com/python/typeshed/tree/main/stubs/protobuf

If stubtest fails for this PR:

• Leave this PR open (as a reminder, and to prevent stubsabot from opening another PR)
• Fix stubtest failures in another PR, then close this PR

Note that you will need to close and re-open the PR in order to trigger CI