Fix URL toString

Author: alxhotel

lib/client/http-tracker.js

@@ -126,7 +126,7 @@ class HTTPTracker extends Tracker {
     this.cleanupFns.push(cleanup)
 
     let request = get.concat({
-      url: parsedUrl,
+      url: parsedUrl.toString(),
       agent: agent,
       timeout: common.REQUEST_TIMEOUT,
       headers: {