community[patch]: Add Cookie Support to Fetch Method (#16673)

- **Description:** This change allows the `_fetch` method in the
`WebBaseLoader` class to utilize cookies from an existing
`requests.Session`. It ensures that when the `fetch` method is used, any
cookies in the provided session are included in the request. This
enhancement maintains compatibility with existing functionality while
extending the utility of the `fetch` method for scenarios where cookie
persistence is necessary.
- **Issue:** Not applicable (new feature),
- **Dependencies:** Requires `aiohttp` and `requests` libraries (no new
dependencies introduced),
- **Twitter handle:** N/A

Co-authored-by: Joao Almeida <[email protected]>

libs/community/langchain_community/document_loaders/web_base.py

@@ -132,6 +132,7 @@ async def _fetch(
                         url,
                         headers=self.session.headers,
                         ssl=None if self.session.verify else False,
+                        cookies=self.session.cookies.get_dict(),
                     ) as response:
                         return await response.text()
                 except aiohttp.ClientConnectionError as e: