* Deprecate prepare_seq2seq_batch * Fix last tests * Apply suggestions from code review Co-authored-by: Lysandre Debut <lysandre@huggingface.co> Co-authored-by: Suraj Patil <surajp815@gmail.com> * More review comments Co-authored-by: Lysandre Debut <lysandre@huggingface.co> Co-authored-by: Suraj Patil <surajp815@gmail.com>