Address linting failure (?)

Author: kevin-bates

jupyter_server/gateway/gateway_client.py

@@ -18,7 +18,6 @@
 from jupyter_events import EventLogger
 from tornado import web
 from tornado.httpclient import AsyncHTTPClient, HTTPClientError, HTTPResponse
-from tornado.httputil import HTTPHeaders
 from traitlets import (
     Bool,
     Float,
@@ -42,7 +41,7 @@
 MESSAGE_KEY = "msg"
 
 if ty.TYPE_CHECKING:
-    from http.cookies import Morsel
+    from tornado.httputil import HTTPHeaders
 
 
 class GatewayTokenRenewerMeta(ABCMeta, type(LoggingConfigurable)):  # type: ignore[misc]
@@ -631,7 +630,7 @@ def load_connection_args(self, **kwargs):
 
         return kwargs
 
-    def update_cookies(self, headers: HTTPHeaders) -> None:
+    def update_cookies(self, headers: "HTTPHeaders") -> None:
         """Update cookies from response headers"""
 
         if not self.accept_cookies: