Update changelog

Author: jorgecotillo

src/Resources/Resources/ChangeLog.md

@@ -21,6 +21,7 @@
 ## Upcoming Release
 * Fixed bug with `PSResource` where some constructors left `SubscriptionId` property unassigned/null.  [#10783]
 * Added support for creating and updating Template Spec in Bicep file [#15313]
+* Use JsonExtensions to serialize deserialize JSON objects to ensure we use custom serialization settings [#15552]
 
 ## Version 4.2.0
 * Allowed naming the deployment when testing deployments [#11497]