Update CHANGELOG.md

Author: daymxn

firebase-vertexai/CHANGELOG.md

@@ -16,6 +16,9 @@
 * [feature] Enable response generation in multiple modalities. (#6901)
 * [changed] **Breaking Change**: Removed the `LiveContentResponse.Status` class, and instead have nested the status
   fields as properties of `LiveContentResponse`. (#6906)
+* [changed] **Breaking Change**: Removed the `LiveContentResponse` class, and instead have provided subclasses
+  of `LiveServerMessage` that match the responses from the model. (#6910)
+* [feature] Added support for the `id` field on `FunctionResponsePart` and `FunctionCallPart`. (#6910)
 
 
 # 16.3.0