Remove unused design-time namespaces from ConvertWindow.axaml for cleanup

src/PicView.Avalonia.MacOS/Views/ConvertWindow.axaml

@@ -3,14 +3,9 @@
     ExtendClientAreaChromeHints="SystemChrome"
     ExtendClientAreaTitleBarHeightHint="-1"
     SizeToContent="WidthAndHeight"
-    d:DesignHeight="450"
-    d:DesignWidth="800"
-    mc:Ignorable="d"
     x:Class="PicView.Avalonia.MacOS.Views.ConvertWindow"
     xmlns="https://github.com/avaloniaui"
-    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:main="clr-namespace:PicView.Avalonia.Views.Main;assembly=PicView.Avalonia"
-    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
     <main:ConvertView />
 </Window>