Latest OpenAI models don't support system prompts

[dangirsh]

Using o1-mini or o1-preview fails with:

Error from the service API:

Unsupported value: 'messages[0].role' does not support 'system' with this model.

[dangirsh]

Ah, they don't yet support streaming...

[rksm]

Yeah, we can switch to non-streamed responses instead.