[Distutils] Setuptools adopts distutils

I’m pleased to announce the release of Setuptools 48, which adopts the distutils codebase from CPython per pypa/setuptools#417<https://github.com/pypa/setuptools/issues/417> and pypa/packaging-problems#127<https://github.com/pypa/packaging-problems/issues/127>. Given the amount of change this effort involved, it’s likely unstable and thus the major version bump. Please report issues at the Setuptools issue tracker. I’ll be around today (IRC, Gitter, Slack) to either disable the functionality or add an escape hatch if needed.