Make setup sheebang use python3

Also drop "coding: utf-8" implied by python3

Author: philpep

setup.py

@@ -1,5 +1,4 @@
-#!/usr/bin/env python
-# coding: utf-8
+#!/usr/bin/env python3
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at