www/py-django-happenings: Deprecate and set to expire

• Upstream's repository seems stale and no longer maintained. There was no official release at PyPI since 2015 and the code isn't compatible with Django 2.2 or later.
  
  Thus deprecate the port and set an expiration date.

PR: 245644
Approved by: Kevin Golding <ports@caomhin.org> (maintainer)