Refs #23919 -- Removed most of remaining six usage

Thanks Tim Graham for the review.

django/db/migrations/loader.py

@@ -1,6 +1,6 @@
 import os
 import sys
-from importlib import import_module
+from importlib import import_module, reload
 
 from django.apps import apps
 from django.conf import settings
@@ -97,7 +97,7 @@ class MigrationLoader(object):
                     continue
                 # Force a reload if it's already loaded (tests need this)
                 if was_loaded:
-                    six.moves.reload_module(module)
+                    reload(module)
             self.migrated_apps.add(app_config.label)
             directory = os.path.dirname(module.__file__)
             # Scan for .py files

django/db/migrations/questioner.py

@@ -5,7 +5,6 @@ import sys
 from django.apps import apps
 from django.db.models.fields import NOT_PROVIDED
 from django.utils import datetime_safe, timezone
-from django.utils.six.moves import input
 
 from .loader import MigrationLoader
 

django/db/migrations/serializer.py

@@ -1,3 +1,4 @@
+import builtins
 import collections
 import datetime
 import decimal
@@ -10,7 +11,7 @@ from importlib import import_module
 from django.db import models
 from django.db.migrations.operations.base import Operation
 from django.db.migrations.utils import COMPILED_REGEX_TYPE, RegexObject
-from django.utils import datetime_safe, six
+from django.utils import datetime_safe
 from django.utils.encoding import force_text
 from django.utils.functional import LazyObject, Promise
 from django.utils.timezone import utc
@@ -305,7 +306,7 @@ class TypeSerializer(BaseSerializer):
                 return string, set(imports)
         if hasattr(self.value, "__module__"):
             module = self.value.__module__
-            if module == six.moves.builtins.__name__:
+            if module == builtins.__name__:
                 return self.value.__name__, set()
             else:
                 return "%s.%s" % (module, self.value.__name__), {"import %s" % module}