NumPy: build script not finding correct python version [UPDATE]

[Rich Shepard]

On Sun, 3 Jan 2021, Rich Shepard wrote:

> I'm trying to rebuild numpy-1.18.2 using the newly installed Python-3.9.1.
> The script fails when running setup.py:
> Traceback (most recent call last):
>  File "setup.py", line 32, in <module>
>    raise RuntimeError("Python version >= 3.5 required.")
> RuntimeError: Python version >= 3.5 required.

Okay. Further research taught me that setup.py has been replaced with
setuptools so I need to learn how to convert the build script to setuptools
rather than setup.py.

Rich