title: The field items.Item.owner was declared with a lazy reference to 'items.user', but app 'items' doesn't provide model 'user'
body: <p>I have extended User Django model using <code>AbstractUser</code> and I have pointed <code>AUTH_USER_MODEL = 'items.User'</code> in my  <code>settings/base.py</code>, then I repointed all the FK to 'items.User'( was User before the change), but I am getting this error in every class I have mentioned 'items.User' when I run  <code>python manage.py migrate</code></p>
  <p>Approach 1</p>
  <pre><code>======items/models.py=======
  from django.contrib.auth.models import AbstractUser
  class User(AbstractUser):
      bio = models.TextField(max_length=500, null=True, blank=True)
      birth_date = models.DateField(null=True, blank=True)
      address = models.CharField(max_length=100,null=True, blank=True)
  -----------------------------------------------
  ======core/settings/base.py=======
  ....
  ALLOWED_HOSTS = []
  AUTH_USER_MODEL = 'items.User'
  ....
  -----------------------------------------------
  =====contracts/models.py=======
  
  class Contract(models.Model):
      .......
      owner = models.ForeignKey('items.User', on_delete=models.CASCADE)
      .........
  </code></pre>
  <p>Approach 2
  I have imported User model from core.settings.base.py</p>
  <pre><code>======core/settings/base.py=====
  ....
  ALLOWED_HOSTS = []
  AUTH_USER_MODEL = 'items.User'
  ....
  -----------------------------------------------
  =======contracts/model.py=====
  from core.settings.base import AUTH_USER_MODEL
  User = AUTH_USER_MODEL
  
  class Contract(models.Model):
      .......
      owner = models.ForeignKey('items.User', on_delete=models.CASCADE)
      .........
  </code></pre>
  <p>and still getting the same error, do I need to drop Db or something because I kind of start to think about a conflict with migrations file with the new change(kind of circulation-alike issue)!!???</p>