www/py-django-netfields: Update to 1.2.2

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

Changelog:

https://github.com/jimfunk/django-postgresql-netfields/blob/v1.2.2/CHANGELOG

PR: 245311
Approved by: maintainer timeout (14 days)