use the @cloudron/superagent module

src/routes/test/backups-test.js

@@ -8,7 +8,7 @@
 const backups = require('../../backups.js'),
     common = require('./common.js'),
     expect = require('expect.js'),
-    superagent = require('../../superagent.js');
+    superagent = require('@cloudron/superagent');
 
 const BACKUP_FOLDER = '/tmp/backup_test';