[Quantization] import torch.fx only if torch.__version__ >= 1.8

wanchen.swc

2023-03-30 0438b966d6d9ef89fdd7a8d112d6e03b34122b1e

 setup.py

@@ -13,7 +13,7 @@
    "install": [
        "setuptools>=38.5.1",
        # "configargparse>=1.2.1",
        "typeguard>=2.7.0",
        "typeguard<=2.13.3",
        "humanfriendly",
        "scipy>=1.4.1",
        # "filelock",