Refs #23919 -- Removed encoding preambles and future imports

tests/model_inheritance/models.py

@@ -11,8 +11,6 @@ Model inheritance exists in two varieties:
 
 Both styles are demonstrated here.
 """
-from __future__ import unicode_literals
-
 from django.db import models
 from django.utils.encoding import python_2_unicode_compatible
 

tests/model_inheritance/test_abstract_inheritance.py

@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 from django.contrib.contenttypes.fields import (
     GenericForeignKey, GenericRelation,
 )

tests/model_inheritance/tests.py

@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 from operator import attrgetter
 
 from django.core.exceptions import FieldError, ValidationError