Fix data io for generic PandasTransformComponent

[RobbeSneyders]

I ran into an issue when using the generic evaluate_ragas component.

component = RetrieverEval(
    module="langchain.llms",
    llm_name="OpenAI",
    llm_kwargs={"openai_api_key": os.environ["OPENAI_KEY"]},
    produces={
        "context_precision": pa.float32(),
        "context_relevancy": pa.float32(),
    },
)

Lead to the following error:

ValueError: Fields ['context_precision', 'context_relevancy'] defined in output dataset but not found in dataframe

Because we were not using the operation_spec yet for the PandasTransformComponent. I think we can reduce the chance of similar errors in the future by only passing the operation_spec to the component, but then we'll need to include the other information from the component spec in there as well.

[mrchtr]

Thanks @RobbeSneyders!