Fix invocation python2 -> python3

Change-Id: Ic78da9c03e99f59d142c93394051bbc2751f0205
diff --git a/pySim/card_handler.py b/pySim/card_handler.py
index bb33833..eaa838b 100644
--- a/pySim/card_handler.py
+++ b/pySim/card_handler.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
 """ pySim: card handler utilities