Add retry for flaky tests in CI (#4755)

test/srt/test_fp8_kvcache.py

@@ -9,11 +9,12 @@ from sglang.test.test_utils import (
     DEFAULT_SMALL_MODEL_NAME_FOR_TEST_QWEN,
     DEFAULT_TIMEOUT_FOR_SERVER_LAUNCH,
     DEFAULT_URL_FOR_TEST,
+    CustomTestCase,
     popen_launch_server,
 )
 
 
-class TestFp8KvcacheBase(unittest.TestCase):
+class TestFp8KvcacheBase(CustomTestCase):
     model_config = None
 
     @classmethod