Fix dragscroll package name.

Thanks to xet7 !

client/components/boards/boardBody.js

@@ -1,6 +1,6 @@
 import { ReactiveCache } from '/imports/reactiveCache';
 import { TAPi18n } from '/imports/i18n';
-import dragscroll from 'dragscroll';
+import dragscroll from '@wekanteam/dragscroll';
 
 const subManager = new SubsManager();
 const { calculateIndex } = Utils;