Qt for Python (PySide/Shiboken)

Can anyone help me shed some light on why I can't build PySide 6.3.0?: https://gist.github.com/keithel/2b18e36471b46225ff005ceb84e6abaf ImportError: cannot import name 'build_py' from 'setuptools._distutils.command' (/home/vagrant/Build/swift-nav/console_pp/py39/lib/python3.9/site-packages/setuptools/_distutils/command/__init__.py) setuptools/_distutils/command/build_py.py exists, and does define a class called build_py...