Refs #23919 -- Removed six.<various>_types usage

Thanks Tim Graham and Simon Charette for the reviews.

tests/order_with_respect_to/models.py

@@ -3,7 +3,6 @@ Tests for the order_with_respect_to Meta attribute.
 """
 
 from django.db import models
-from django.utils import six
 
 
 class Question(models.Model):
@@ -18,7 +17,7 @@ class Answer(models.Model):
         order_with_respect_to = 'question'
 
     def __str__(self):
-        return six.text_type(self.text)
+        return self.text
 
 
 class Post(models.Model):