fix: export video scans error

Pixiview/Illust/ViewIllustPage.xaml.cs

@@ -743,9 +743,13 @@ namespace Pixiview.Illust
                 var success = await Task.Run(ugoira.ExportVideo);   // ugoira.ExportGif
                 if (success != null)
                 {
+#if DEBUG
+                    msg = ResourceHelper.ExportSuccess;
+#else
                     var result = await FileStore.SaveVideoToGalleryAsync(success);
 
                     msg = result ?? ResourceHelper.ExportSuccess;
+#endif
                 }
             }