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

wanchen.swc

2023-03-30 0438b966d6d9ef89fdd7a8d112d6e03b34122b1e

 funasr/runtime/python/libtorch/README.md

@@ -31,7 +31,7 @@

    ```shell
    git clone https://github.com/alibaba/FunASR.git && cd FunASR
    cd funasr/runtime/python/funasr_torch
    cd funasr/runtime/python/libtorch
    python setup.py build
    python setup.py install
    ```