update to einops 0.4, which is torchscript jit friendly

Author: lucidrains

setup.py

@@ -3,7 +3,7 @@
 setup(
   name = 'vit-pytorch',
   packages = find_packages(exclude=['examples']),
-  version = '0.27.0',
+  version = '0.27.1',
   license='MIT',
   description = 'Vision Transformer (ViT) - Pytorch',
   author = 'Phil Wang',
@@ -15,7 +15,7 @@
     'image recognition'
   ],
   install_requires=[
-    'einops>=0.3',
+    'einops>=0.4.1',
     'torch>=1.6',
     'torchvision'
   ],