Updated Git branch "master" to "main" for Django repository.

Author: felixxm

tox.ini

@@ -1,7 +1,7 @@
 [tox]
 envlist =
     {py36,py37,py38,py39}-django{22,30,31,32}-test
-    {py38,py39}-django{master}-test
+    {py38,py39}-django{main}-test
     isort
     flake
 
@@ -20,7 +20,7 @@ deps =
     django30: Django>=3.0,<3.1
     django31: Django>=3.1,<3.2
     django32: Django==3.2a1
-    djangomaster: https://github.com/django/django/archive/master.tar.gz
+    djangomain: https://github.com/django/django/archive/main.tar.gz
 
 [testenv:isort]
 basepython = python3.9