fixed lint error

packages/app/src/server/service/in-app-notification.ts

@@ -1,5 +1,5 @@
 import Crowi from '../crowi';
-import InAppNotification from '~/server/models/in-app-notification';
+import { InAppNotification } from '~/server/models/in-app-notification';
 
 class InAppNotificationService {
 
@@ -30,7 +30,6 @@ class InAppNotificationService {
   }
 
   removeActivity = async function(activity) {
-    const InAppNotification = require('../models/in-app-notification')(this.crowi);
     const { _id, target, action } = activity;
     const query = { target, action };
     const parameters = { $pull: { activities: _id } };