www/py-django-solo: Update to 2.2.0
- Switch back to PyPI as the sdist is available there. GH was used as a temporary solution in a16febdfdb0c to get some fixes for Django 2.2.
Changelog since 2.0.0:
https://github.com/lazybird/django-solo/blob/2.2.0/CHANGES
PR: 276328
Approved by: Ivan Rozhuk (maintainer)