Feature description

Perplexity sonar-pro returns citations in response.citations field ignored in ragbits.core.llms.litellm.LiteLLM._call.

The ask is to include response.citations in outputs returned by _call, or otherwise support a method that exposes citations, perhaps generate_with_metadata.

I think you can just add this

            if hasattr(response, 'citations'): # type: ignore
                outputs.citations = response.citations  # type: ignore

(#383)

Motivation

User wanting to use perplexity has to use api directly, missing out on tracing etc.

Additional context

here's what perplexity api returns
dict_keys(['id', 'choices', 'created', 'model', 'object', 'usage', 'citations'])