update django 1.11 to stable release in tox

Author: auvipy

tox.ini

@@ -26,7 +26,7 @@ deps =
         django18: Django>=1.8,<1.9
         django19: Django>=1.9,<1.10
         django110: Django>=1.10,<1.11
-        django111: Django>=1.11rc1,<2.0
+        django111: Django>=1.11,<2.0
         djangomaster: https://github.com/django/django/archive/master.tar.gz
         -rrequirements/requirements-testing.txt
         -rrequirements/requirements-optionals.txt