Do not carry Request::params over to a redirect's Location

A request sent with send(Request) and params got those params appended
to the Location of a redirect that had no query, on the same origin or
another one. The Location alone names the next target, as it already
did for Get/Post(path, params).

httplib.h

@@ -9352,6 +9352,7 @@ inline bool redirect(T &cli, Request &req, Response &res,
                      Error &error) {
   Request new_req = req;
   new_req.path = path;
+  new_req.params.clear();
   new_req.redirect_count_ -= 1;
 
   if (res.status == StatusCode::SeeOther_303 &&