Update OnPropertyChanged after merge.

src/Avalonia.Base/Layout/Layoutable.cs

@@ -790,7 +790,7 @@ namespace Avalonia.Layout
         {
         }
 
-        protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> change)
+        protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
         {
             base.OnPropertyChanged(change);