Update CHANGELOG.md

Author: daymxn

firebase-vertexai/CHANGELOG.md

@@ -15,7 +15,7 @@
 * [fixed] Fixed an issue with `LiveSession` not converting exceptions to `FirebaseVertexAIException`. (#6870)
 * [feature] Enable response generation in multiple modalities. (#6901)
 * [changed] Removed the `LiveContentResponse.Status` class, and instead have nested the status
-  fields as properties of `LiveContentResponse`. (#TODO)
+  fields as properties of `LiveContentResponse`. (#6906)
 
 
 # 16.3.0