be explicit about parallel_tool_call option for streams

[mottoslo]

Confirm this is a feature request for the Python library and not the underlying OpenAI API.

• This is a feature request for the Python library

Describe the feature or improvement you're requesting

For runs created by opening a stream, parallel_tool_call options could only be set to false using the extra_body argument, because the runs.stream function does not accept parallel_tool_call as an argument.
Because multiple tool outputs can only be submitted in a single request, managing and syncing the state of each tool_calls can add unnecessary complication in some use_cases. In that case, it requires testing to find out that turning off the parallel_tool_call option is also possible in streams, since documentation for parallel_tool_call is only provided for non-stream approach.

I've checked that parallel_tool_call option works as expected if passed in as extra_body. Although this works fine for me, I think such option should be explicitly set as keyword argument.

Additional context

I would like to try and make a PR for this if my request turns out to be valid. Thanks

[RobertCraigie]

Thanks for the report, the parallel_tool_calls request param will be added in the next release #1598