[BugFix] Fix tool call finish reason in streaming case

[maxdebayser]

When a named function is passed to tool_choice with streaming the finish_reason was "stop" instead of "tool_calls".

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[maxdebayser]

cc: @njhill @tjohnson31415

[tjohnson31415]

Actually, this behavior may be expected in the OpenAI spec 🤔

Check if the model has made a tool_call. This is the case either if the "finish_reason" is "tool_calls" or if the "finish_reason" is "stop" and our API request had forced a function call
...
This handles the edge case where if we forced the model to call one of our functions, the finish_reason will actually be "stop" instead of "tool_calls"

REF: https://platform.openai.com/docs/guides/function-calling/edge-cases

[maxdebayser]

Actually, this behavior may be expected in the OpenAI spec

Yeah, I'll test to see what OpenAI returns. If that is the case, then it's the non-streaming case that is inconsistent.

[maxdebayser]

@tjohnson31415 , you're right. I've tested with gpt4 on the OpenAI platform and the behavior is as follows:

OpenAI
	named function	auto
unary	stop	tool_calls
stream	stop	tool_calls

So actually the non-streaming case for named function needs to be changed to return stop instead of tool_calls

[njhill]

Thanks @maxdebayser!