text: Title: Search filter for Djoser auth/users view ?
  Body: Hi,
  Is there a way to add a search filter (https://www.django-rest-framework.org/api-guide/filtering/#searchfilter) to the `auth/users/` GET endpoint of Djoser ?
  I would like to add a username filter without having to use an extra endpoint.
  Would it make sense to create a pull request to add a setting to specify some custom filters on the views ?