project: fix injecting error messages from action script

This uses an internal API that has changed in 0aeea3c4 (Validation
message translation, 2021-01-06)

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

@@ -7,7 +7,7 @@ portal = context.getPortalObject()
 line_portal_type = "Sale Order Line"
 request = context.REQUEST
 from string import zfill
-from Products.ERP5Type.Document import newTempBase
+from Products.PythonScripts.standard import Object
 from Products.ERP5Type.Message import translateString
 
 context.log('original listbox', listbox)
@@ -65,9 +65,10 @@ for line in line_list:
     else:
       line_dict['source_project_relative_url'] = result[0].getRelativeUrl()
     if error_message:
-      error = newTempBase(context, key)
-      error.edit(error_text=error_message)
-      validation_errors['listbox_source_project_title_new_%s' % key] = error
+      validation_errors['listbox_source_project_title_new_%s' % key] = Object(
+          field_id='listbox_source_project_title_new_%s' % key,
+          getMessage=lambda translateString: translateString(error_message),
+      )
   listbox.append(line_dict)
   i += 1