Remove expired ports:

2020-05-25 www/py-django-annotations: No longer maintained, not compatible with Django 2.0+
2020-05-25 www/py-django-registration-defaults: No longer maintained, not compatible with newer versions of www/py-django-registration
2020-05-25 devel/py-django-rq-dashboard: No longer maintained, not compatible with Django 2.0+, please use devel/py-django-rq instead
2020-05-25 www/py-django_openstack_auth: No longer maintained, code was merged into 13.x release of www/py-horizon