[requires.io] dependency update

Author: requires

tox.ini

@@ -14,7 +14,7 @@ deps =
     dj19: Django>=1.9,<1.10
     dj110: Django>=1.10,<1.11
     dj111: Django>=1.11,<2.0
-    dj20: Django==2.0b1
+    dj20: Django==2.0rc1
     coverage
     django_jinja
     html5lib