Update CollectionCustomEditor.cs

Author: brunomikoski

Scripts/Editor/CustomEditors/CollectionCustomEditor.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
-using JetBrains.Annotations;
 using UnityEditor;
 using UnityEditor.Callbacks;
 using UnityEditor.Compilation;