Deprecated distutils bdist_wininst is going to be removed

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I proposed to remove the bdist_winstinst command from distutils in Python 3.9:

• https://bugs.python.org/issue39541
• https://discuss.python.org/t/remove-distutils-bdist-wininst-command/3115
• bpo-39541: Remove distutils bdist_wininst command python/cpython#18329

Problem: setuptools always uses it on all platforms at: setuptools/command/install_scripts.py, line 35:

  bw_cmd = self.get_finalized_command("bdist_wininst")

See #857 which is a closed duplicated which proposed different options to fix the issue.