fixed invalid thread for clipboard task

src/PixiEditor/Views/Windows/HelloTherePopup.axaml.cs

@@ -227,7 +227,7 @@ internal partial class HelloTherePopup : PixiEditorPopup
 
     private void CheckHasClipboardInImage()
     {
-        Task.Run(async () =>
+        Dispatcher.UIThread.InvokeAsync(async () =>
         {
             hasImageInClipboard = await ClipboardController.IsImageInClipboard();
         }).ContinueWith(_ =>

src/global.json

@@ -1,7 +1,7 @@
 {
   "sdk": {
     "version": "8.0.405",
-    "rollForward": "latestMajor",
+    "rollForward": "latestMinor",
     "allowPrerelease": false
   }
 }