Turn off preview for color node

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Data/Nodes/Input/ColorNode.cs

             UpdateNodeAfterDeserialization();
         }
 
-        public override bool hasPreview
-        {
-            get { return true; }
-        }
-
         public sealed override void UpdateNodeAfterDeserialization()
         {
             AddSlot(new MaterialSlot(kOutputSlotId, kOutputSlotName, kOutputSlotName, SlotType.Output, SlotValueType.Vector4, Vector4.zero));