change connect_timeout to float

Author: oeway

jupyter_server_proxy/handlers.py

@@ -319,7 +319,7 @@ def proxy_request_headers(self):
     def proxy_request_options(self):
         '''A dictionary of options to be used when constructing
         a tornado.httpclient.HTTPRequest instance for the proxy request.'''
-        return dict(follow_redirects=False, connect_timeout=250, request_timeout=300.0)
+        return dict(follow_redirects=False, connect_timeout=250.0, request_timeout=300.0)
 
     def check_xsrf_cookie(self):
         '''