display modal form in the bootstrap4 theme

flask_admin/static/admin/js/bs4_modal.js

 // fixes "content does not load remote modal on clicked modal button"
 $('body').on('click.modal.data-api', '[data-toggle="modal"]', function () {
     $($(this).data("target") + ' .modal-content').load($(this).attr('href'));
-});
\ No newline at end of file
+});