[stubsabot] Bump protobuf to ~=6.31.1

[github-actions[bot]]

Release: https://pypi.org/pypi/protobuf/6.31.1 Homepage: https://developers.google.com/protocol-buffers/ Repository: https://github.com/protocolbuffers/protobuf Typeshed stubs: https://github.com/python/typeshed/tree/main/stubs/protobuf

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