CI: pin setuptools on 1.1.x
top answer on stack overflow is to pin https://stackoverflow.com/questions/63663362/django-python3-on-install-i-get-parent-module-setuptools-not-loaded

also see https://github.com/MacPython/pandas-wheels/pull/97#issuecomment-684938715

Note: 50.0.1 released a hour ago but still the same. https://dev.azure.com/pandas-dev/pandas/_build/results?buildId=41325&view=logs&j=a67b4c4c-cd2e-5e3c-a361-de73ac9c05f9&t=9a6bfc0f-544f-57f9-291f-bf4b75b05642