Fix error spam in TAA Export dialog

[williamchange]

E 0:00:12:021   texture.gd:74 @ in_thread_get_texture(): /root/MainWindow/ExportTAA/VBoxContainer/TextureRect: The caller thread can't call the function `queue_redraw()` on this node. Use `call_deferred()` or `call_deferred_thread_group()` instead.
  <C++ Error>   Condition "!is_accessible_from_caller_thread()" is true.
  <C++ Source>  scene/main/canvas_item.cpp:473 @ queue_redraw()
  <Stack Trace> texture.gd:74 @ in_thread_get_texture()
                multi_renderer.gd:132 @ thread_loop()