remove unused using statements

Author: davidkline-ms

Assets/MixedRealityToolkit.Tests/EditModeTests/Core/Utilities/PackageManifestUpdaterTests.cs

@@ -4,8 +4,6 @@
 using Microsoft.MixedReality.Toolkit.Utilities.Editor;
 using NUnit.Framework;
 using System;
-using System.Collections;
-using System.Collections.Generic;
 using UnityEngine;
 
 namespace Microsoft.MixedReality.Toolkit.Tests.EditMode.Core.Utilities.Editor