[CI/Build] Replace math.isclose with pytest.approx (#18703)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

tests/entrypoints/openai/correctness/test_mteb.py

@@ -1,5 +1,4 @@
 # SPDX-License-Identifier: Apache-2.0
-import math
 import os
 
 import pytest
@@ -39,4 +38,4 @@ def test_mteb(server):
     print("SentenceTransformer main score: ", st_main_score)
     print("Difference: ", st_main_score - vllm_main_score)
 
-    assert math.isclose(st_main_score, vllm_main_score, rel_tol=1e-4)
+    assert st_main_score == pytest.approx(vllm_main_score, rel=1e-4)