use the @cloudron/superagent module

src/dns/hetzner.js

@@ -17,7 +17,7 @@ const assert = require('assert'),
     dig = require('../dig.js'),
     dns = require('../dns.js'),
     safe = require('safetydance'),
-    superagent = require('../superagent.js'),
+    superagent = require('@cloudron/superagent'),
     waitForDns = require('./waitfordns.js');
 
 const ENDPOINT = 'https://dns.hetzner.com/api/v1';