PyTorch 1.7.0 Compatibility Updates (#1233)

* torch 1.7.0 compatibility updates

* add inference verification

models/yolo.py

@@ -165,7 +165,6 @@ class Model(nn.Module):
         print('Fusing layers... ')
         for m in self.model.modules():
             if type(m) is Conv and hasattr(m, 'bn'):
-                m._non_persistent_buffers_set = set()  # pytorch 1.6.0 compatability
                 m.conv = fuse_conv_and_bn(m.conv, m.bn)  # update conv
                 delattr(m, 'bn')  # remove batchnorm
                 m.forward = m.fuseforward  # update forward