updates for vllm v0.11.0 (#21)

* updates for vllm v0.11.0

* package can be installed up to python 3.10

* fix the formatting error

* fix formatting with ruff

Feature/#17 (#18)

* upgrade to the latest vllm

* delete deprecated GuidedDecoding

Add chat function at mock vllm 'LLM' instance (#16)

* redirect import vllm_mock library

* add chat function and its test codes

* fix some ruff errors

* delete src path