Merge pull request #4340 from AvaloniaUI/convert-osx-number-key-gestures

convert D0 to D9 to 0 to 9 string.

src/Avalonia.Native/OsxUnicodeKeys.cs

@@ -140,6 +140,11 @@ namespace Avalonia.Native.Interop
             }
             else
             {
+                if (key >= Key.D0 && key <= Key.D9)
+                {
+                    return key.ToString().Replace("D", "");
+                }
+                
                 return key.ToString().ToLower();
             }
         }