bug: Latest openai library breaks some unit tests

[vblagoje]

As our CI picked up the latest release of openai https://pypi.org/project/openai/1.14.0/ we experienced CI test failures.

The errors seem to stem from changes in non-public API of openai library. The stack trace of one the errors is:

==================================== ERRORS ====================================
___ ERROR at setup of TestOpenAIChatGenerator.test_run_with_params_streaming ___

    @pytest.fixture
    def mock_chat_completion_chunk():
        """
        Mock the OpenAI API completion chunk response and reuse it for tests
        """
    
        class MockStream(Stream[ChatCompletionChunk]):
            def __init__(self, mock_chunk: ChatCompletionChunk, *args, **kwargs):
                super().__init__(*args, **kwargs)
                self.mock_chunk = mock_chunk
    
            def __stream__(self) -> Iterator[ChatCompletionChunk]:
                # Yielding only one ChatCompletionChunk object
                yield self.mock_chunk
    
        with patch("openai.resources.chat.completions.Completions.create") as mock_chat_completion_create:
            completion = ChatCompletionChunk(
                id="foo",
                model="gpt-4",
                object="chat.completion.chunk",
                choices=[
                    Choice(
                        finish_reason="stop", logprobs=None, index=0, delta=ChoiceDelta(content="Hello", role="assistant")
                    )
                ],
                created=int(datetime.now().timestamp()),
                usage={"prompt_tokens": 57, "completion_tokens": 40, "total_tokens": 97},
            )
>           mock_chat_completion_create.return_value = MockStream(completion, cast_to=None, response=None, client=None)

test/components/generators/conftest.py:57: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
test/components/generators/conftest.py:37: in __init__
    super().__init__(*args, **kwargs)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <conftest.mock_chat_completion_chunk.<locals>.MockStream object at 0x7be0a80fe610>

    def __init__(
        self,
        *,
        cast_to: type[_T],
        response: httpx.Response,
        client: OpenAI,
    ) -> None:
        self.response = response
        self._cast_to = cast_to
        self._client = client
>       self._decoder = client._make_sse_decoder()
E       AttributeError: 'NoneType' object has no attribute '_make_sse_decoder'

../../../.local/share/hatch/env/virtual/haystack-ai/4LlKeELt/test/lib/python3.8/site-packages/openai/_streaming.py:39: AttributeError

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