Update mutes.js (#5882)

app/javascript/mastodon/actions/mutes.js

 import api, { getLinks } from '../api';
 import { fetchRelationships } from './accounts';
-import { openModal } from '../../mastodon/actions/modal';
+import { openModal } from './modal';
 
 export const MUTES_FETCH_REQUEST = 'MUTES_FETCH_REQUEST';
 export const MUTES_FETCH_SUCCESS = 'MUTES_FETCH_SUCCESS';
@@ -100,4 +100,4 @@ export function toggleHideNotifications() {
   return dispatch => {
     dispatch({ type: MUTES_TOGGLE_HIDE_NOTIFICATIONS });
   };
-}
\ No newline at end of file
+}