fix: add json(content_type=None) to fix bing_x content-type

hummingbot/core/web_assistant/connections/data_types.py

@@ -111,7 +111,7 @@ def headers(self) -> Optional[Mapping[str, str]]:
         return headers_
 
     async def json(self) -> Any:
-        json_ = await self._aiohttp_response.json()
+        json_ = await self._aiohttp_response.json(content_type=None)
         return json_
 
     async def text(self) -> str: