convert : add Poro-34B-chat tokenizer support (#7713)

* support for Poro chat pre-tokenizer

* add support for Poro pre-tokenizer

* Update convert-hf-to-gguf-update.py

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

* Change Poro-34B-chat to poro-chat

* Change Poro-34B-chat to poro-chat

* Update convert-hf-to-gguf-update.py

* Update llama.cpp

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Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>