🚀 The feature

Currently the llms/gemini.py is migrated to the new google-genai SDK but the embedchain, embedder and llm still have dependency on the old deprecated google-generativeai SDK.

We should update our codebase to use the new SDK throughout.

Motivation, pitch

With the release of Gemini 2.0, the google-generativeai Python SDK has been deprecated. Google now recommends migrating to the new unified python-genai SDK.

I can make a PR for this if it sounds good.