fix registration hook

lib/register-authenticator.js

@@ -189,7 +189,10 @@ const digestChallenge = async(req, res, next) => {
   const {stats} = req.srf.locals;
   const {
     account_sid,
-    registration_hook,
+    registration_hook_url,
+    registration_hook_method,
+    registration_hook_username,
+    registration_hook_password,
     webhook_secret
   } = req.locals;
   // Cannot detect account, reject register request