Minor accessibility improvements

Signed-off-by: marcin mikołajczak <git@mkljczk.pl>

app/soapbox/components/modal_root.js

@@ -1,5 +1,6 @@
 import React from 'react';
 import PropTypes from 'prop-types';
+import 'wicg-inert';
 import { injectIntl, FormattedMessage, defineMessages } from 'react-intl';
 import { connect } from 'react-redux';
 import { openModal } from '../actions/modal';