Fix Build Error

Author: Hexer10

UI/MainWindow.xaml.cs

@@ -11,6 +11,7 @@
 using System.Windows.Threading;
 using DiscordRPC;
 using MahApps.Metro;
+using Spcode.Interop.Updater;
 using Spcode.UI.Components;
 using Xceed.Wpf.AvalonDock;
 using Xceed.Wpf.AvalonDock.Layout;