fix(koa->upload): fix the error that occurs when uploading files in the test server of Koa.

[electroluxcode]

问题好像出在koa对于form-data的上传数据结构变了，按照原来的代码在test-server下面启动并且上传文件会有如下报错，查看了一下目前的数据结构是 PersistentFile

TypeError [ERR_INVALID_ARG_TYPE]: The "path" argument must be of type string or an instance of Buffer or URL. Received undefined
    at ReadStream (node:internal/fs/streams:171:5)
    at new ReadStream (E:\myProject\vue-vben-admin\node_modules\.pnpm\graceful-fs@4.2.11\node_modules\graceful-fs\graceful-fs.js:299:28)
    at Object.createReadStream (E:\myProject\vue-vben-admin\node_modules\.pnpm\graceful-fs@4.2.11\node_modules\graceful-fs\graceful-fs.js:341:12)
    at fileFunc (E:\myProject\vue-vben-admin\apps\test-server\service\FileService.ts:13:23)
    at FileService.<anonymous> (E:\myProject\vue-vben-admin\apps\test-server\service\FileService.ts:49:7)
    at Generator.next (<anonymous>)
    at E:\myProject\vue-vben-admin\apps\test-server\service\FileService.ts:8:71
    at new Promise (<anonymous>)
    at __awaiter (E:\myProject\vue-vben-admin\apps\test-server\service\FileService.ts:4:12)
    at FileService.upload (E:\myProject\vue-vben-admin\apps\test-server\service\FileService.ts:22:16) {
  code: 'ERR_INVALID_ARG_TYPE'
}
[nodemon] app crashed - waiting for file changes before starting...