Add support for OpenAI's o1 models by making max_response_tokens optional

The other prerequisite seems to be not using a `prompt` (`prompt: null`),
but we already supported this.

It'd be nice to add an optional `max_completion_tokens` parameter as
well, for the benefit of the o1 models, but this is not yet supported by
async-openai.
Possibly tracked here: https://github.com/64bit/async-openai/issues/272

docs/sample-provider-configs/openai-o1.yml

@@ -0,0 +1,24 @@
+base_url: https://api.openai.com/v1
+api_key: YOUR_API_KEY_HERE
+text_generation:
+  model_id: o1-mini
+  # o1 models do not support a system prompt
+  prompt: null
+  temperature: 1.0
+  # o1 models do not support max_response_tokens.
+  # They use `max_completion_tokens` as an alternative,
+  # but we don't support it yet (see https://github.com/64bit/async-openai/issues/272).
+  max_response_tokens: null
+  max_context_tokens: 128000
+speech_to_text:
+  model_id: whisper-1
+text_to_speech:
+  model_id: tts-1-hd
+  voice: onyx
+  speed: 1.0
+  response_format: opus
+image_generation:
+  model_id: dall-e-3
+  style: vivid
+  size: 1024x1024
+  quality: standard