Fixed docstring for cohere model regarding unavailability of prune_he… (#33253)
* Fixed docstring for cohere model regarding unavailability of prune_head() methods
The docstring mentions that cohere model supports prune_heads() methods. I have fixed the docstring by explicitly mentioning that it doesn't support that functionality.
* Update src/transformers/models/cohere/modeling_cohere.py
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Co-authored-by: Lysandre Debut <hi@lysand.re>