fix(compat): make it work with latest hyper

This is known to work with the master of hyper. It's probably OK
to keep it, preparing for the next release and under the assupmtion
that I will not be releasing binaries for a while.

src/mako/api/lib/mbuild.mako

@@ -726,7 +726,7 @@ else {
                 };
             % endif
                 let mut client = &mut *self.hub.client.borrow_mut();
-                let mut req = client.borrow_mut().request(${method_name_to_variant(m.httpMethod)}, url.as_ref())
+                let mut req = client.borrow_mut().request(${method_name_to_variant(m.httpMethod)}, &url)
                     .header(UserAgent(self.hub._user_agent.clone()))\
                     % if default_scope: