fix: Change default model of CohereReranking

[fa-ina-tic]

Description

Hello :) Thank you for your maintenance.
The previous default model for Cohere, rerank-multilingual-v2.0, has been deprecated, so I’ve updated the default to rerank-multilingual-v3.0.

Type of change

• New features (non-breaking change).
• Bug fix (non-breaking change).
• Breaking change (fix or feature that would cause existing functionality not to work as expected).

Checklist

• I have performed a self-review of my code.
• I have added thorough tests if it is a core feature.
• There is a reference to the original bug report and related work.
• I have commented on my code, particularly in hard-to-understand areas.
• The feature is well documented.