Add reasoning_content field to ResponseMessage

[panghy]

Mainly to support seeing CoT reasoning details with "DeepSeek": https://api-docs.deepseek.com/guides/reasoning_model

[sashirestela]

Have you verified that the deepseek-reasoner model is working?

I've tried this chat resquest and it responds with an empty body:

{
    "model": "deepseek-reasoner",
    "messages": [
        {
            "role": "user",
            "content": "9.11 and 9.8, which is greater?"
        }
    ],
    "stream": false,
    "max_tokens": 8192
}

[sashirestela]

@panghy The deepseek-reasoner model is not working in its API. I see this issue reported by several users on the DeepSeek's Discord Channel

[sashirestela]

@panghy This will be part of the next release

[panghy]

Thanks! I was using it and was noticing that it's not able to access the reasoning content.