www/py-django-reversion: Update to 3.0.7

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

• Make USES block separate from non-related variables.

Changelog:

https://github.com/etianen/django-reversion/blob/v3.0.7/CHANGELOG.rst

PR: 245312
Approved by: maintainer timeout (14 days)