Move task to another thread

I don't know whether this is the prefered method.

Signed-off-by: TheKodeToad <TheKodeToad@proton.me>

launcher/ui/dialogs/ExportMrPackDialog.h

@@ -39,6 +39,4 @@ class ExportMrPackDialog : public QDialog {
     const InstancePtr instance;
     Ui::ExportMrPackDialog* ui;
     PackIgnoreProxy* proxy;
-
-    void runExport();
 };