root.html: protect $ symbol from overwriting (#7589)

$ can be overwritten by the jQuery loaded by django-debug-toolbar in the
messages fadeout callback, it prevents that.

gadjo/templates/gadjo/root.html

@@ -60,7 +60,12 @@
     {% endfor %}
 </ul>
 <script>
-$(document).ready(function() { $('.messages').delay(5000).fadeOut('slow'); });
+(function () {
+    var $ = jQuery;
+    $(document).ready(function() {
+      $('.messages').delay(5000).fadeOut('slow');
+    });
+})();
 </script>
 {% endif %}
 {% endblock %}