add django 4.0 support

Author: Umar Asghar

CHANGES.rst

@@ -9,6 +9,7 @@ master (unreleased)
 - Dropped support for Django 3.0
 - Added suppport for Django 3.1
 - Added suppport for Django 3.2
+- Added support for Django 4.0
 
 4.0 (2020-01-04)
 -----------------

README.rst

@@ -22,6 +22,7 @@ directory or on ReadTheDocs: https://django-robots.readthedocs.io/
 
 Supported Django versions
 -------------------------
+* Django 4.0
 * Django 3.2
 * Django 3.1
 * Django 2.2

setup.py

@@ -46,5 +46,6 @@ def read(*parts):
         'Framework :: Django :: 2.2',
         'Framework :: Django :: 3.1',
         'Framework :: Django :: 3.2',
+        'Framework :: Django :: 4.0',
     ]
 )

tox.ini

@@ -2,7 +2,7 @@
 envlist =
     # list of supported Django/Python versions:
     # https://docs.djangoproject.com/en/3.1/faq/install/#what-python-version-can-i-use-with-django
-    py{36,37,38,39}-dj{22,31,32}
+    py{36,37,38,39}-dj{22,31,32,40}
     py{38,39}-djmain
     py38-{lint,docs}
 
@@ -27,6 +27,7 @@ deps =
     dj22: django>=2.2,<2.3
     dj31: django>=3.1,<3.2
     dj32: django>=3.2,<3.3
+    dj40: django>=4.0a1,<4.1
     djmain: https://github.com/django/django/archive/main.tar.gz
 
 [testenv:py38-lint]