Refs #23919 -- Removed six.PY2/PY3 usage

Thanks Tim Graham for the review.

tests/test_runner/test_debug_sql.py

@@ -5,7 +5,6 @@ from django.db import connection
 from django.test import TestCase
 from django.test.runner import DiscoverRunner
 from django.utils import six
-from django.utils.encoding import force_text
 
 from .models import Person
 
@@ -43,8 +42,6 @@ class TestDebugSQL(unittest.TestCase):
         ).run(suite)
         runner.teardown_databases(old_config)
 
-        if six.PY2:
-            stream.buflist = [force_text(x) for x in stream.buflist]
         return stream.getvalue()
 
     def test_output_normal(self):