[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/diffusion/lora/test_base_linear.py

@@ -5,10 +5,13 @@ from __future__ import annotations
 
 from dataclasses import dataclass
 
+import pytest
 import torch
 
 from vllm_omni.diffusion.lora.layers.base_linear import DiffusionBaseLinearLayerWithLoRA
 
+pytestmark = [pytest.mark.core_model, pytest.mark.cpu]
+
 
 @dataclass
 class _DummyLoRAConfig: