[BUG] Types for promptflow-evals evaluator classes

[pamelafox]

Describe the bug

The type for config is listed as AzureOpenAIModelConfiguration:
https://github.com/microsoft/promptflow/blob/main/src/promptflow-evals/promptflow/evals/evaluators/_relevance/_relevance.py#L19

However, my hope is to also use OpenAIModelConfiguration with it, and my guess is that it's not intentionally set to Azure only. Can that type be a union or the base class?

[github-actions]

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[pamelafox]

I don't believe any more input is needed from me. (The stalebot in this repo seems to be tuned to respond really quickly to perceived stalneness, btw).