www/py-django-markdownx: Update to 3.0.1

• Also assign the port to Django 2.2 (current LTS release) as Django 1.11 is End-of-Life.

• Enforce UTF-8 environments for Python <= 3.6 to avoid errors during the configuration phase.

• Make USES block separate from non-related variables.

Changelog:

https://github.com/neutronX/django-markdownx/releases

PR: 245325
Approved by: maintainer timeout (14 days)