[networking] Add strict Request extension checking (#7604)

Authored by: coletdjnz
Co-authored-by: pukkandan <pukkandan.ytdlp@gmail.com>

yt_dlp/networking/_urllib.py

@@ -385,6 +385,11 @@ class UrllibRH(RequestHandler, InstanceStoreMixin):
         if self.enable_file_urls:
             self._SUPPORTED_URL_SCHEMES = (*self._SUPPORTED_URL_SCHEMES, 'file')
 
+    def _check_extensions(self, extensions):
+        super()._check_extensions(extensions)
+        extensions.pop('cookiejar', None)
+        extensions.pop('timeout', None)
+
     def _create_instance(self, proxies, cookiejar):
         opener = urllib.request.OpenerDirector()
         handlers = [