Update package to google-genai in examples/Search_reranking_using_embeddings.ipynb

[Jenniebn]

Update package to google-genai in examples/Search_reranking_using_embeddings.ipynb

• Updated google-generativeai to use google-genai package instead.
• Updated outputs and tested locally.
• Refactored imports
• Restructured the sections and updated instructions
• Formatted with nbfmt and nblint tool