[CI] Add pytest markers to current tests and update the doc. (#577)

Signed-off-by: Alicia <115451386+congw729@users.noreply.github.com>
Co-authored-by: Hongsheng Liu <liuhongsheng4@huawei.com>

tests/entrypoints/openai_api/test_serving_speech.py

@@ -16,6 +16,8 @@ from vllm_omni.entrypoints.openai.serving_speech import (
 )
 from vllm_omni.outputs import OmniRequestOutput
 
+pytestmark = [pytest.mark.core_model, pytest.mark.cpu]
+
 logger = logging.getLogger(__name__)