Changed the version number to come from the assembly version.

src/Avalonia.Dialogs/AboutAvaloniaDialog.xaml

@@ -42,7 +42,7 @@
                  FontSize="32"
                  Grid.Row="1"/>
             
-      <TextBlock Text="v11"
+      <TextBlock Text="{Binding Version}"
                  FontWeight="Regular"
                  HorizontalAlignment="Center"
                  FontSize="14"

src/Avalonia.Dialogs/AboutAvaloniaDialog.xaml.cs

@@ -12,7 +12,7 @@ namespace Avalonia.Dialogs
     {
         private static readonly Version s_version = typeof(AboutAvaloniaDialog).Assembly.GetName().Version;
 
-        public static string Version { get; } = s_version.ToString(2);
+        public static string Version { get; } = $@"v{s_version.ToString(2)}";
 
         public static bool IsDevelopmentBuild { get; } = s_version.Revision == 999;