Changing iteritems in templates to items for Py2/3 compatibility

Author: sp-lyang

templates/pip.conf.j2

@@ -1,6 +1,6 @@
-{% for section,config in python_pip_config.iteritems() | sort %}
+{% for section,config in python_pip_config.items() | sort %}
 [{{section}}]
-{% for k,v in config.iteritems() | sort %}
+{% for k,v in config.items() | sort %}
 {% if v is iterable and v is not string %}
 {{k}} =
 {% for item in v %}