Update tox config.

tox.ini

@@ -1,27 +1,25 @@
 [tox]
 envlist =
-    py{36,37,38}-django{21,22,30,31,trunk}
+    py{36,37,38}-dj{21,22,30,31,trunk}
     flake8
 
 [testenv]
 deps =
     freezegun==0.3.12
     -rrequirements-test.txt
-    django22: Django==2.2.*
-    django21: Django==2.1.*
-    django30: Django==3.0.*
-    django31: Django==3.1.*
-    djangotrunk: https://github.com/django/django/archive/master.tar.gz
+    dj22: Django==2.2.*
+    dj21: Django==2.1.*
+    dj30: Django==3.0.*
+    dj31: Django==3.1.*
+    djtrunk: https://github.com/django/django/archive/master.tar.gz
 ignore_outcome =
-    djangotrunk: True
+    djtrunk: True
 passenv =
     CI
-    TRAVIS
-    TRAVIS_*
-
+    GITHUB_*
+usedevelop = True
 commands =
-    pip install -e .
-    py.test {posargs}
+    pytest {posargs}
 
 [testenv:flake8]
 basepython =
@@ -37,3 +35,9 @@ ignore =
     W503  ; line break before binary operator
     E402  ; module level import not at top of file
     E501  ; line too long
+
+[gh-actions]
+python =
+    3.6: py36
+    3.7: py37, flake8
+    3.8: py38