fix: max_tokens in O1

[ex0ns]

Description

This bug has been introduced in 89396ae and is assuming that a max_tokens exists for O1 models, which is not the case, failing with a KeyError.

Stacktrace:

  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/tenacity/__init__.py", line 398, in <lambda>
    self._add_action_func(lambda rs: rs.outcome.result())
                                     ^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.runtime/python/lib/python3.12/concurrent/futures/_base.py", line 449, in result
    return self.__get_result()
           ^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.runtime/python/lib/python3.12/concurrent/futures/_base.py", line 401, in __get_result
    raise self._exception
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/tenacity/asyncio/__init__.py", line 114, in __call__
    result = await fn(*args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/llama_index/llms/openai/base.py", line 700, in _achat
    messages=message_dicts, stream=False, **self._get_model_kwargs(**kwargs)
                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/llama_index/llms/openai/base.py", line 427, in _get_model_kwargs
    if self.model in O1_MODELS and base_kwargs["max_tokens"] is not None:
                                   ~~~~~~~~~~~^^^^^^^^^^^^^^
KeyError: 'max_tokens'

We could add a test for _get_model_kwargs but there are no tests for private method in this package.

Version Bump?

Did I bump the version in the pyproject.toml file of the package I am updating? (Except for the llama-index-core package)

• Yes
• No

Type of Change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Your pull-request will likely not be merged unless it is covered by some form of impactful unit testing.

• I added new unit tests to cover this change
• I believe this change is already covered by existing unit tests

Suggested Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added Google Colab support for the newly added notebooks.
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I ran make format; make lint to appease the lint gods