[pygobject] setup.py: default to Python 3

[Christoph Reiter <creiter src gnome org>]

commit b0fbb13783a2ece048a812b233e1fad15c5b8a31
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Tue Jan 23 00:27:32 2018 +0100

    setup.py: default to Python 3
    
    autotools defaults to Python 3 as well, so do the same for
    distutils.

 setup.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/setup.py b/setup.py
old mode 100644
new mode 100755
index ea0d25f3..7ffb11f1
--- a/setup.py
+++ b/setup.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # Copyright 2017 Christoph Reiter <reiter christoph gmail com>
 #
 # This library is free software; you can redistribute it and/or