[Small] Formatter only checks lints in changed files

[cadedaniel]

There are many lint failures which makes new ones easy to miss. This PR makes the linter by default only check changed files using the same logic as used for yapf.

Testing

$ ./format.sh --files vllm/block.py
vLLM yapf: Done
vLLM Pylint:

------------------------------------
Your code has been rated at 10.00/10

$ echo '# long line------------------------------------------------------------------------' >> vllm/block.py
$ ./format.sh
vLLM yapf: Done
vLLM Pylint:
************* Module vllm.block
vllm/block.py:71:0: C0301: Line too long (83/80) (line-too-long)

-----------------------------------
Your code has been rated at 9.70/10

$ ./format.sh --all
vLLM yapf: Done
vLLM Pylint:
************* Module vllm.model_executor.models.internlm
vllm/model_executor/models/internlm.py:265:24: E1136: Value 'state_dict' is unsubscriptable (unsubscriptable-object)
vllm/model_executor/models/internlm.py:275:24: E1136: Value 'state_dict' is unsubscriptable (unsubscriptable-object)
vllm/model_executor/models/internlm.py:293:24: E1136: Value 'state_dict' is unsubscriptable (unsubscriptable-object)
vllm/model_executor/models/internlm.py:307:20: E1136: Value 'state_dict' is unsubscriptable (unsubscriptable-object)
************* Module vllm.model_executor.models.qwen
vllm/model_executor/models/qwen.py:296:24: E1136: Value 'state_dict' is unsubscriptable (unsubscriptable-object)
vllm/model_executor/models/qwen.py:309:20: E1136: Value 'state_dict' is unsubscriptable (unsubscriptable-object)
[rest omitted]

[Yard1]

LGTM!

[zhuohan123]

LGTM! Thanks for your contribution!