[torchao] safetensors integration (#25969)

Signed-off-by: Angel Li <liangel@meta.com>

vllm/model_executor/layers/quantization/torchao.py

@@ -1,10 +1,13 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+import importlib
 import json
+from importlib.util import find_spec
 from typing import Any, Optional
 
 import torch
 import torch.nn.functional as F
+from packaging import version
 from torch.nn.parameter import Parameter
 
 from vllm.logger import init_logger
@@ -23,6 +26,18 @@ from vllm.model_executor.utils import set_weight_attrs
 logger = init_logger(__name__)
 
 
+def torchao_version_at_least(torchao_version: str) -> bool:
+    if find_spec("torchao"):
+        try:
+            if version.parse(importlib.metadata.version("torchao")) >= version.parse(
+                torchao_version
+            ):
+                return True
+        except (ImportError, version.InvalidVersion):
+            return False
+    return False
+
+
 def should_skip(prefix: str, skip_modules: list[str]) -> bool:
     """
     Robust skipping logic: