[networking] Request: Update extensions

Authored by: bashonly

yt_dlp/networking/common.py

@@ -463,9 +463,10 @@ def headers(self, new_headers: Mapping):
         else:
             raise TypeError('headers must be a mapping')
 
-    def update(self, url=None, data=None, headers=None, query=None):
+    def update(self, url=None, data=None, headers=None, query=None, extensions=None):
         self.data = data if data is not None else self.data
         self.headers.update(headers or {})
+        self.extensions.update(extensions or {})
         self.url = update_url_query(url or self.url, query or {})
 
     def copy(self):