Refs #23919 -- Removed encoding preambles and future imports

tests/custom_pk/models.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 Using a custom primary key
 
@@ -6,8 +5,6 @@ By default, Django adds an ``"id"`` field to each model. But you can override
 this behavior by explicitly adding ``primary_key=True`` to a field.
 """
 
-from __future__ import unicode_literals
-
 from django.db import models
 from django.utils.encoding import python_2_unicode_compatible