Wekan: Broken access control in the Excel-export route (`/api/boards/:boardId/exportExcel`)

Wekan is open source kanban built with Meteor. From 9.57 until 9.74, the /api/boards/:boardId/exportExcel route in models/exportExcel.js called the asynchronous exporterExcel.canExport(user) authorization guard from models/server/ExporterExcel.js without awaiting it. The returned Promise was always truthy, so exporterExcel.build(res) ran even when board.isVisibleBy(user) would deny access, allowing any authenticated non-member to download private board card titles, descriptions, lists, swimlanes, members, and metadata. This issue is fixed in version 9.74.