Change helpdesk URL to support.hifis.net

_includes/contact_form.html

@@ -3,7 +3,7 @@
 <script type="text/javascript"
         src="{{ site.directory.vendor | append: 'jquery/dist/jquery.min.js' | strip | relative_url }}">
 </script>
-<script id="zammad_form_script" src="https://hifis-help.hzdr.de/assets/form/form.js"></script>
+<script id="zammad_form_script" src="https://{{ site.helpdesk }}/assets/form/form.js"></script>
 
 <script>
 $(function () {