www/py-dj32-django-auth-ldap: Update to 4.0.0

• Python 3.6 is now gone from the Ports so remove the cruft that was required for it.

• Add a workaround to make the port still buildable with Python's distutils by using the "setup.py" from the previous release.

Changelog:

https://github.com/django-auth-ldap/django-auth-ldap/releases/tag/4.0.0

MFH: 2022Q1
(cherry picked from commit 22de57b9f1d8d88c6a86fda71446614ea7f85757)