Update setuptools to 50.0.1

[pyup-bot]

This PR updates setuptools from 50.0.0 to 50.0.1.

Changelog

50.0.1

-------

* 2357: Restored Python 3.5 support in distutils.util for missing `subprocess._optim_args_from_interpreter_flags`.
* 2358: Restored AIX support on Python 3.8 and earlier.
* 2361: Add Python 3.10 support to _distutils_hack. Get the 'Loader' abstract class
from importlib.abc rather than importlib.util.abc (alias removed in Python
3.10).

Links

• PyPI: https://pypi.org/project/setuptools
• Changelog: https://pyup.io/changelogs/setuptools/
• Repo: https://github.com/pypa/setuptools

[duckinator]

bors r+

[bors]

Build succeeded:

• FreeBSD LANG:C.UTF-8 LC_ALL:C.UTF-8 PYTHON:3.7
• FreeBSD LANG:C.UTF-8 LC_ALL:C.UTF-8 PYTHON:3.8
• FreeBSD LANG:en_US.UTF-8 LC_ALL:en_US.UTF-8 PYTHON:3.6
• Lint
• Linux container:python:3.6-slim
• Linux container:python:3.7-slim
• Linux container:python:3.8-slim
• macOS
• Windows container:python:3.6-windowsservercore-1809
• Windows container:python:3.7-windowsservercore-1809