net.http: fix a bug with ? in new_request

vlib/net/http/http.v

@@ -30,7 +30,7 @@ pub mut:
 }
 
 pub fn new_request(method Method, url_ string, data string) ?Request {
-	url := if method == .get { url_ + '?' + data } else { url_ }
+	url := if method == .get && !url_.contains('?') { url_ + '?' + data } else { url_ }
 	// println('new req() method=$method url="$url" dta="$data"')
 	return Request{
 		method: method