Prepare release notes

Author: labkey-nicka

CHANGE.txt

@@ -5,10 +5,11 @@ LabKey Python Client API News
 What's New in the LabKey 4.0.0 package
 ==============================
 
-*Release date: 07/08/2025*
+*Release date: 09/16/2025*
 - Add save_rows API to query module
     - Accessible via API wrappers e.g. api.query.save_rows
 - Update the minimum required version of Python to 3.10
+- Add "derivationDataScope" to PropertyDescriptor class. Thanks @eso-xyme!
 
 What's New in the LabKey 3.4.0 package
 ==============================