Fixed #24299 -- Added an auth migration to ensure contenttypes is migrated.

Without this migration, the auth signal handlers will fail if migrating
only auth.

django/contrib/auth/migrations/0006_require_contenttypes_0002.py

+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('auth', '0005_alter_user_last_login_null'),
+        ('contenttypes', '0002_remove_content_type_name'),
+    ]
+
+    operations = [
+        # Ensure the contenttypes migration is applied before sending
+        # post_migrate signals (which create ContentTypes).
+    ]