erp5_item: add delete_action to draft in item_workflow

bt5/erp5_item/WorkflowTemplateItem/portal_workflow/item_workflow/states/draft.xml

@@ -28,6 +28,8 @@
             <key> <string>transitions</string> </key>
             <value>
               <tuple>
+                <string>delete</string>
+                <string>delete_action</string>
                 <string>validate</string>
                 <string>validate_action</string>
               </tuple>