Fixed #8520 -- Corrected a dumb typo in the call to password_change in...

Fixed #8520 -- Corrected a dumb typo in the call to password_change in django/contrib/admin/sites.py. Thanks Karen Tracey for catching this.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8523 bcc190cf-cafb-0310-a4f2-bffc1f526a37