feat!: Update UPGRADE.md for Twilio library changes

Author: manisha1997

UPGRADE.md

@@ -6,9 +6,8 @@ posted here._
 ## [2024-03-07] 9.x.x to 10.x.x
 ### Overview
 
-##### Twilio Python Helper Library’s major version 10.0.0 is now available. We ensured that you can upgrade to Python helper Library 10.0.0 version without any breaking changes of existing apis
+##### Twilio Python Helper Library’s major version 10.0.0 is now available. Twiml Voice has a breaking change. Please refer to docs.
 
-Behind the scenes Python Helper is now auto-generated via OpenAPI with this release. This enables us to rapidly add new features and enhance consistency across versions and languages.
 Twiml Attribute speechModel is now of type string.
 
 ## [2024-02-20] 8.x.x to 9.x.x