Add missing « in "Back to admin interface" link

Add the missing "«" in "Back to admin interface" link in JI
/admin/edit/<user_id> for constency with other pages in the admin
section.

securedrop/journalist_templates/edit_account.html

@@ -4,7 +4,7 @@
 {% if user %}
   {# Only admins may edit usernames and admin status #}
   <h1>{{ gettext('Edit user "{user}"').format(user=user.username) }}</h1>
-  <p><a href="/admin">{{ gettext('Back to admin interface') }}</a></p>
+  <p><a href="/admin">« {{ gettext('Back to admin interface') }}</a></p>
   <h2>{{ gettext('Change Name and Admin Status') }}</h2>
   <form method="post">
     <input name="csrf_token" type="hidden" value="{{ csrf_token() }}">