Rename Django's dev branch to main.

More information: https://groups.google.com/g/django-developers/c/tctDuKUGosc/
Refs: https://github.com/django/django/pull/14048

.github/workflows/test.yml

@@ -11,7 +11,7 @@ jobs:
       max-parallel: 5
       matrix:
         python-version: ['3.6', '3.7', '3.8', '3.9']
-        django-version: ['2.2', '3.0', '3.1', 'master']
+        django-version: ['2.2', '3.0', '3.1', 'main']
 
     steps:
     - uses: actions/checkout@v2

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 envlist =
-    py{36,37,38,39}-dj{22,30,31,master}
+    py{36,37,38,39}-dj{22,30,31,main}
     lint
     sphinx
     readme
@@ -17,7 +17,7 @@ DJANGO =
     2.2: dj22
     3.0: dj30
     3.1: dj31
-    master: djmaster
+    main: djmain
 
 [testenv]
 deps =
@@ -25,7 +25,7 @@ deps =
     dj22: Django>=2.2,<3.0
     dj30: Django>=3.0,<3.1
     dj31: Django>=3.1,<3.2
-    djmaster: https://github.com/django/django/archive/master.tar.gz
+    djmain: https://github.com/django/django/archive/main.tar.gz
     nose
 commands =
     pip install -e .
@@ -33,7 +33,7 @@ commands =
     python -Wd {envbindir}/demo test --cover-package=django_downloadview --cover-package=demoproject --cover-xml {posargs: tests demoproject}
     pip freeze
 ignore_outcome =
-    djmaster: True
+    djmain: True
 
 [testenv:lint]
 deps =