Add pytest markers for core model and diffusion tests

Signed-off-by: 汪志鹏 <wangzhipeng628@gmail.com>
Signed-off-by: princepride <wangzhipeng628@gmail.com>

tests/diffusion/kernels/mot/test_mot_norm.py

@@ -22,6 +22,8 @@ from vllm.model_executor.layers.layernorm import rms_norm
 
 from vllm_omni.diffusion.layers.mot.mot_layernorm import MoTRMSNorm
 
+pytestmark = [pytest.mark.core_model, pytest.mark.diffusion, pytest.mark.gpu]
+
 # ---------------------------------------------------------------------------
 # Constants
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