Hi,

is there any reason why msgpack requires the latest setuptools version to build? Would it be possible to relax the version or even remove the version constraint entire? setuptools >= 80.9.0 is causing issues for downstream packagers that cannot update setuptools to latest version.

Background:
setuptools have had several major breaking changes over the last years. We are expecting more breaking changes in the future. Some breaking changes are done in purpose, others introduced accidentally by lack of testing. Our downstream build system currently has setuptools!=72.0.0,!=77.0.1,!=77.0.2,!=78.0.0,!=78.0.1,<=80.8.0 to block bad releases.