remove spurious import

Author: alan412

src/App.tsx

@@ -48,7 +48,6 @@ import { mutatorOpenListener } from './blocks/mrc_param_container'
 import { TOOLBOX_UPDATE_EVENT } from './blocks/mrc_mechanism_component_holder';
 import { antdThemeFromString } from './reactComponents/ThemeModal';
 import { useTranslation } from 'react-i18next';
-import { setup } from './blocks/mrc_event_handler';
 
 /** Storage key for shown toolbox categories. */
 const SHOWN_TOOLBOX_CATEGORIES_KEY = 'shownPythonToolboxCategories';