tick communication API (#3154)

UnitySDK/Assets/ML-Agents/Scripts/Academy.cs

         "docs/Learning-Environment-Design-Academy.md")]
     public abstract class Academy : MonoBehaviour
     {
-        const string k_ApiVersion = "API-12";
+        const string k_ApiVersion = "API-13";
         const int k_EditorTrainingPort = 5004;
 
         /// Temporary storage for global gravity value

ml-agents-envs/mlagents_envs/environment.py

 class UnityEnvironment(BaseEnv):
     SCALAR_ACTION_TYPES = (int, np.int32, np.int64, float, np.float32, np.float64)
     SINGLE_BRAIN_ACTION_TYPES = SCALAR_ACTION_TYPES + (list, np.ndarray)
-    API_VERSION = "API-12"
+    API_VERSION = "API-13"
 
     def __init__(
         self,