[Bugfix] Migrate to REGEX Library to prevent catastrophic backtracking (#18454)

Signed-off-by: Crucifixion-Fxl <xmufxl@gmail.com>
Co-authored-by: Crucifixion-Fxl <xmufxl@gmail.com>

tests/tool_use/test_tool_choice_required.py

@@ -1,10 +1,10 @@
 # SPDX-License-Identifier: Apache-2.0
 import json
-import re
 from copy import deepcopy
 from unittest.mock import MagicMock
 
 import pytest
+import regex as re
 from pydantic import TypeAdapter
 
 from vllm.entrypoints.openai.protocol import (ChatCompletionRequest,
@@ -333,4 +333,4 @@ def test_streaming_output_valid(output, empty_params, delta_len):
             combined_messages += message.tool_calls[0].function.arguments
     combined_messages += "}]"
     assert json.loads(combined_messages) == output
-    assert json.dumps(json.loads(combined_messages)) == output_json
+    assert json.dumps(json.loads(combined_messages)) == output_json