Officially test under only active (non EOL) Django releases

.github/workflows/build.yml

@@ -13,8 +13,6 @@ jobs:
     strategy:
       matrix:
         python-version: ["3.6", "3.7", "3.8", "3.9", "3.10"]
-        django: ["2.2", "3.0", "3.1", "3.2", "4.0"]
-
     steps:
     - uses: actions/checkout@v2
     - name: Set up Python ${{ matrix.python-version }}
@@ -28,8 +26,6 @@ jobs:
         if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
     - name: Linting
       run: flake8
-    - name: Run unittests
-      env:
-        TOX_ENV: py${{ matrix.python-version}}-django${{ matrix.django }}
-      run: |
-        tox -e $TOX_ENV
+    # Environments are selected using tox-gh-actions configuration in tox.ini.
+    - name: Test with tox
+      run: tox

requirements.txt

@@ -1,2 +1,2 @@
 pytz
-Django>=1.5
+Django>=2.2

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py{3.6,3.7,3.8,nightly}-django2.2,py{3.6,3.7,3.8,3.9,3.10,nightly}-django{3.0,3.1,3.2,4.0,master},lint,docs,functional
+envlist = py{3.6,3.7,3.8,nightly}-django2.2,py{3.6,3.7,3.8,3.9,3.10,nightly}-django{3.2,4.0,master},lint,docs,functional
 
 [testenv]
 passenv = *
@@ -17,20 +17,19 @@ basepython =
 deps =
     -rrequirements-tests.txt
     django2.2: Django>=2.2,<2.3
-    django3.0: Django>=3.0,<3.1
-    django3.1: Django>=3.1,<3.2
     django3.2: Django>=3.2,<3.3
     django4.0: Django>=4.0,<4.1
     djangomaster: https://github.com/django/django/archive/master.zip
 commands = {posargs:coverage run runtests.py}
 
+# Configure which test environments are run for each Github Actions Python version.
 [gh-actions]
 python =
-    3.6: py36
-    3.7: py37
-    3.8: py38
-    3.9: py39
-    3.10: py310
+    3.6: py36-django{22,32}
+    3.7: py37-django{22,32}
+    3.8: py38-django{22,32,40}
+    3.9: py39-django{22,32,40}
+    3.10: py310-django{22,32,40}
 
 [testenv:lint]
 basepython = python