[FIX] base: P3.5 - P3.6 compatibility

In P3.6, the error message has changed.

odoo/addons/base/tests/test_qweb.py

@@ -5,6 +5,7 @@ import collections
 import json
 import os.path
 import re
+import sys
 
 from lxml import etree
 
@@ -481,6 +482,8 @@ class TestQWebNS(TransactionCase):
             """
         })
         error_msg = "Can't convert 'int' object to str implicitly"
+        if sys.version_info >= (3, 6):
+            error_msg = "must be str, not int"
         with self.assertRaisesRegexp(QWebException, error_msg):
             view1.render()