Fixed #16002 - test failure due to missing `from __future__ import with_statement`

Thanks to julien for the report

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16213 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/regressiontests/csrf_tests/tests.py

@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+from __future__ import with_statement
 import warnings
 
 from django.test import TestCase