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

wanchen.swc

2023-03-30 0438b966d6d9ef89fdd7a8d112d6e03b34122b1e

 funasr/layers/label_aggregation.py

@@ -79,4 +79,4 @@
        else:
            olens = None

        return output, olens
        return output.to(input.dtype), olens