code_style: remove unused code

Signed-off-by: leo <longshuang@msn.cn>

src/Views/EnhancedSelectableTextBlock.cs

@@ -1,20 +0,0 @@
-using System;
-
-using Avalonia;
-using Avalonia.Controls;
-
-namespace SourceGit.Views
-{
-    public class EnhancedSelectableTextBlock : SelectableTextBlock
-    {
-        protected override Type StyleKeyOverride => typeof(SelectableTextBlock);
-
-        protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
-        {
-            base.OnPropertyChanged(change);
-
-            if (change.Property == TextProperty)
-                UpdateLayout();
-        }
-    }
-}