Make use of the seed parameter in the LLM-based evaluators using the OpenAI API

[davidsbatista]

Is your feature request related to a problem? Please describe.
The LLM-based evaluators are non-deterministic, and this can be an issue in replicating and comparing evaluation results.

Describe the solution you'd like
One possible solution is to use the seed parameter when using the OpenAI-based LLMs: https://platform.openai.com/docs/api-reference/chat/create

• seed: integer or null
• This feature is in Beta. If specified, our system will make a best effort to sample deterministically, such that repeated requests with the same seed and parameters should return the same result.