www/py-django-filer: Update to 3.4.1

• Switch to the PEP517 build framework.

• Update WWW to point to the actual upstream repository.

• Also change to the more preferred DISTVERSION and take MAINTAINER'ship due three consecutive timeouts.

Changelog since 3.1.0:

https://github.com/django-cms/django-filer/blob/3.4.1/CHANGELOG.rst

PR: 291708
Approved by: maintainer timeout (5+ weeks)