add max_completions_tokens for o1 series models

[chococola]

Describe the change
For new o1 series models attribute max_tokens not working. In documentation this field marks deprecated.
OpenAi introduced new attribute max_completion_tokens.

To manage costs with the o1 series models, you can limit the total number of tokens the model generates (including both reasoning and completion tokens) by using the [max_completion_tokens](https://platform.openai.com/docs/api-reference/chat/create#chat-create-max_completion_tokens) parameter.

In previous models, the max_tokens parameter controlled both the number of tokens generated and the number of tokens visible to the user, which were always equal. However, with the o1 series, the total tokens generated can exceed the number of visible tokens due to the internal reasoning tokens.

Because some applications might rely on max_tokens matching the number of tokens received from the API, the o1 series introduces max_completion_tokens to explicitly control the total number of tokens generated by the model, including both reasoning and visible completion tokens. This explicit opt-in ensures no existing applications break when using the new models. The max_tokens parameter continues to function as before for all previous models.

Provide OpenAI documentation link
https://platform.openai.com/docs/api-reference/chat/create#chat-create-max_tokens
https://platform.openai.com/docs/api-reference/chat/create#chat-create-max_completion_tokens
https://platform.openai.com/docs/guides/reasoning/controlling-costs
https://community.openai.com/t/why-was-max-tokens-changed-to-max-completion-tokens/938077

Describe your solution
Update ChatCompletionRequest model

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.03%. Comparing base (774fc9d) to head (be774ca).
Report is 51 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #857      +/-   ##
==========================================
+ Coverage   98.46%   99.03%   +0.57%     
==========================================
  Files          24       26       +2     
  Lines        1364     1452      +88     
==========================================
+ Hits         1343     1438      +95     
+ Misses         15        8       -7     
  Partials        6        6              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[chococola]

@sashabaranov please take a look to the PR 🙃

[sashabaranov]

@chococola great catch, thank you for the PR!

Could we also panic when o1 is used and max_tokens≠0?

[sashabaranov]

Or just return an error, panic might be too much :)

[chococola]

@chococola great catch, thank you for the PR!

Could we also panic when o1 is used and max_tokens≠0?

panic would be to much, and propably break backwards capabilities for oldest models.

Maybe we should mark attribute as deprecated ? or leave the comment?

return an error

in all places ? and what about batch requests ?

[sashabaranov]

@chococola let's cover the most frequent chat completion + streaming case, all other cases would eventually be covered by other PRs :D

[chococola]

@sashabaranov i add validation check for o1 series models and add some validation for fields which are limited in beta
https://platform.openai.com/docs/guides/reasoning/beta-limitations

[sashabaranov]

Wow, o1 is a can of worms! Thank you so much for looking so deeply into this! 🙌🏻