change deprecated dirOnly option

src/gui/tandem_run_dialog/tandemrundialog.cpp

@@ -407,7 +407,7 @@ TandemRunDialog::selectTdfFolder()
       QString default_tdf_location =
         settings.value("path/tandemrun_tdf_directory", "").toString();
       QFileDialog directories_dialog;
-      directories_dialog.setFileMode(QFileDialog::DirectoryOnly);
+      directories_dialog.setOption(QFileDialog::ShowDirsOnly, true);
       directories_dialog.setOption(QFileDialog::DontUseNativeDialog, true);
       directories_dialog.setWindowTitle("Select the timsTOF folders");
       QListView *lView = directories_dialog.findChild<QListView *>("listView");