fix: removed remnants of check_port

Author: ryshoooo

jupyter_server_proxy/config.py

@@ -100,7 +100,6 @@ def make_handlers(base_url, server_processes):
             sp.timeout,
             sp.absolute_url,
             sp.port,
-            sp.check_port,
             sp.mappath,
             sp.request_headers_override,
             sp.rewrite_response,