[bugfix] Make FoodCollector heuristic playable (#4147)

* Make FoodCollector heuristic playable

* Update changelog

Project/Assets/ML-Agents/Examples/FoodCollector/Scripts/FoodCollectorAgent.cs

 
     public override void Heuristic(float[] actionsOut)
     {
+        actionsOut[0] = 0f;
+        actionsOut[1] = 0f;
+        actionsOut[2] = 0f;
         if (Input.GetKey(KeyCode.D))
         {
             actionsOut[2] = 2f;

com.unity.ml-agents/CHANGELOG.md

 - The Barracuda dependency was upgraded to 1.0.0 (#4118)
 #### ml-agents / ml-agents-envs / gym-unity (Python)
 - Added new Google Colab notebooks to show how to use `UnityEnvironment'. (#4117)
+- Fixed issue with FoodCollector when playing with keyboard. (#4147)
 
 ### Bug Fixes
 #### com.unity.ml-agents (C#)