Fixed slot bug

MaterialGraphProject/Assets/GraphFramework/SerializableGraph/Editor/Drawing/Presenters/GraphNodePresenter.cs

             foreach (var slot in slots)
             {
                 var data = CreateInstance<GraphAnchorPresenter>();
+                data.capabilities &= ~Capabilities.Movable; 
+
                 if (slot.isOutputSlot)
                 {
                     outputAnchors.Add(data);