Fix Color node recompilation

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

                 if ((value.color == m_Color.color) && (value.mode == m_Color.mode))
                     return;
                 m_Color = value;
-                Dirty(ModificationScope.Graph);
+                Dirty(ModificationScope.Node);
             }
         }