ui: fix recursive import of header_login.html

Author: JakobMiesner

invenio_administration/templates/semantic-ui/invenio_theme/header_login.html

@@ -7,8 +7,6 @@
   under the terms of the MIT License; see LICENSE file for more details.
 #}
 
-{%- extends "invenio_theme/header_login.html" %}
-
 {%- block profile_admin %}
   {% set ns = namespace(admin_menu=False) %} 
   {%- for item in current_menu.submenu('profile-admin').children if item.visible %}