migrations: Downgrade dependencies to auth
migrations: Downgrade dependencies to auth

Some of the applications which use django-helusers might be using older
Django than 1.11.  Change the dependency to earlier migration to allow
using django-helusers with older Django versions (1.8, 1.9 or 1.10).

City-of-Helsinki/django-helusers,City-of-Helsinki/django-helusers