Fix another duplicated line in the changelog...

com.unity.ml-agents/CHANGELOG.md

 #### com.unity.ml-agents / com.unity.ml-agents.extensions (C#)
 #### ml-agents / ml-agents-envs / gym-unity (Python)
 
-### Major Changes
-#### com.unity.ml-agents (C#)
-- Make com.unity.modules.unityanalytics an optional dependency. (#5109)
-
 ## [1.9.0-preview] - 2021-03-17
 ### Major Changes
 #### com.unity.ml-agents (C#)