use a more universally-available japanese font

Program.cs

@@ -506,7 +506,7 @@ public static class Util {
 
   public static OpenTK.Windowing.Common.Input.Image[] RenderAppIcon() {
     int size = 64;
-    Font font = SystemFonts.CreateFont("MS PMincho", size, FontStyle.Bold);
+    Font font = SystemFonts.CreateFont("MS Mincho", size, FontStyle.Bold);
     TextOptions options = new(font);
     Image<Rgba32> image = MakeImage(size, size);
     IBrush brush = Brushes.Solid(Color.Black);