Bumped to released Django version 4.0.0 (#1022)

Author: sliverc

tox.ini

@@ -11,7 +11,7 @@ deps =
     django30: Django>=3.0,<3.1
     django31: Django>=3.1,<3.2
     django32: Django>=3.2,<3.3
-    django40: Django>=4.0rc1,<5.0
+    django40: Django>=4.0,<5.0
     drf312: djangorestframework>=3.12,<3.13
     drfmaster: https://github.com/encode/django-rest-framework/archive/master.zip
     -rrequirements/requirements-testing.txt