fix bug on pytorch1.9.1

Author: JingyunLiang

README.md

@@ -31,7 +31,7 @@ This repository is the official PyTorch implementation of Mutual Affine Network
 
 
 ## Requirements
-- Python 3.7, PyTorch == 1.6.0(now have bugs with PyTorch 1.9.0), scipy >= 1.6.3 
+- Python 3.7, PyTorch >= 1.6.0, scipy >= 1.6.3 
 - Requirements: opencv-python
 - Platforms: Ubuntu 16.04, cuda-10.0 & cuDNN v-7.5