fixup! erp5_system_event: Add follow_up_title to 'More Columns' of System Event Module listbox

The term (used for example on HTTPExchange_view/my_follow_up_title ) is
"Follow-up". This will fix testNamingConventions failure.

bt5/erp5_system_event/SkinTemplateItem/portal_skins/erp5_system_event/SystemEventModule_viewAuthenticationEventList/listbox.xml

@@ -80,7 +80,7 @@
                       <list>
                         <tuple>
                           <string>follow_up_title</string>
-                          <string>Follow Up</string>
+                          <string>Follow-up</string>
                         </tuple>
                         <tuple>
                           <string>creation_date</string>