[CI] Try introducing isort. (#3495)

tests/tokenization/test_tokenizer_group.py

@@ -1,14 +1,16 @@
-import os
-import pytest
 import asyncio
+import os
 from unittest.mock import patch
 
+import pytest
 from transformers import AutoTokenizer, PreTrainedTokenizerBase
+
 from vllm.transformers_utils.tokenizer_group import get_tokenizer_group
 from vllm.transformers_utils.tokenizer_group.ray_tokenizer_group import (
     RayTokenizerGroupPool)
 from vllm.transformers_utils.tokenizer_group.tokenizer_group import (
     TokenizerGroup)
+
 from ..conftest import get_tokenizer_pool_config