project: fix a wrong translation

This was creating different message for each number of tasks

bt5/erp5_project/SkinTemplateItem/portal_skins/erp5_project_trade/Delivery_updateTaskFastInputDialog.py

@@ -102,6 +102,5 @@ if create and len(validation_errors) == 0:
               destination_section=delivery_line.getDestinationSection(),
               destination_decision=delivery_line.getDestinationDecision())
   return context.Base_redirect(form_id, keep_items=dict(
-        portal_status_message=translateString('%s Tasks Created.' %(len(listbox),))))
-
+        portal_status_message=translateString('${task_count} Tasks Created.', mapping={'task_count': len(listbox)})))
 return context.Delivery_viewTaskFastInputDialog(listbox=listbox, **kw)