Removed test error preventing Unity from playing (#233)

com.unity.perception/Tests/Editor/UIElementsEditorUtilitiesTests.cs

 using UnityEngine;
 using Object = UnityEngine.Object;
 
+// Disable value is never assigned to warning
+#pragma warning disable 649
 public class UIElementsEditorUtilitiesTests
 {
     //ScriptableObject so we can use ScriptableObject.CreateInstance()