[CLN] core: upgrade to python 3.6

& sort imports

closes odoo/documentation#2975

X-original-commit: 57784a2f90
Signed-off-by: Victor Feyens (vfe) <vfe@odoo.com>

extensions/odoo_theme/__init__.py

@@ -25,7 +25,7 @@ def set_missing_meta(app, pagename, templatename, context, doctree):
     if context.get('meta') is None:  # Pages without title (used with `include::`) have no meta
         context['meta'] = {}
 
-class Monkey(object):
+class Monkey:
     """ Replace patched method of an object by a new method receiving the old one in argument. """
     def __init__(self, obj):
         self.obj = obj