File no-python2.patch of Package python-onnx

Index: onnx-1.6.0/tools/protoc-gen-mypy.py
===================================================================
--- onnx-1.6.0.orig/tools/protoc-gen-mypy.py
+++ onnx-1.6.0/tools/protoc-gen-mypy.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Taken from https://github.com/dropbox/mypy-protobuf/blob/d984389124eae6dbbb517f766b9266bb32171510/python/protoc-gen-mypy
 # (Apache 2.0 License)