[Release] patch step3p5 attention class in v0.15.1 release (#33602)

Signed-off-by: zhewenli <zhewen@inferact.ai>
Co-authored-by: zhewenli <zhewen@inferact.ai>

vllm/model_executor/models/step3p5.py

@@ -21,7 +21,7 @@ from vllm.distributed import (
 )
 from vllm.logger import init_logger
 from vllm.model_executor.layers.activation import SiluAndMul, SwigluStepAndMul
-from vllm.model_executor.layers.attention import Attention
+from vllm.attention.layer import Attention
 from vllm.model_executor.layers.fused_moe import FusedMoE
 from vllm.model_executor.layers.fused_moe.shared_fused_moe import SharedFusedMoE
 from vllm.model_executor.layers.layernorm import GemmaRMSNorm