Updated Goal check system to use new syntax

DOTS_Pong/Assets/Ball.prefab

   m_GameObject: {fileID: 6887475011426345520}
   m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
   m_LocalPosition: {x: 0, y: 0, z: 0}
-  m_LocalScale: {x: 1, y: 1, z: 1}
+  m_LocalScale: {x: 0.7, y: 0.7, z: 0.7}
   m_Children: []
   m_Father: {fileID: 0}
   m_RootOrder: 0

DOTS_Pong/Assets/Scripts/Systems/BallGoalCheckSystem.cs

 using UnityEngine;
 using Unity.Collections;
 using Unity.Mathematics;
+using Unity.Jobs;
-public class BallGoalCheckSystem : ComponentSystem
+public class BallGoalCheckSystem : JobComponentSystem
-	protected override void OnUpdate()
+	protected override JobHandle OnUpdate(JobHandle inputDeps)
-		Entities.WithAll<BallTag>().ForEach((Entity entity, ref Translation trans) => 
-		{
+		Entities
+			.WithAll<BallTag>()
+			.WithStructuralChanges()
+			.ForEach((Entity entity, ref Translation trans) =>
+			{
 			float3 pos = trans.Value;
 			float bound = GameManager.main.xBound;
 
-				PostUpdateCommands.DestroyEntity(entity);
+				EntityManager.DestroyEntity(entity);
-				PostUpdateCommands.DestroyEntity(entity);
+				EntityManager.DestroyEntity(entity);
-		});
+		}).Run();
+
+		return inputDeps;
 	}
 }