cohere[patch]: support request timeout in BaseCohere (#19641)
As in #19346, this PR exposes `request_timeout` in `BaseCohere`, while
`max_retires` is no longer a parameter of the beneath client
(`cohere.Client`) and it is already configured in
`langchain_cohere.llms.Cohere`.
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Co-authored-by: Bagatur <baskaryan@gmail.com>
