Remove support for unsupported Python/Django combinations.

Author: YPCrumble

tox.ini

@@ -3,11 +3,11 @@ envlist =
     lint-py36,
     readme-py36,
     docs-py36,
-    py35-django{111,20,21,22},
-    py36-django{111,20,21,22,30},
-    py37-django{111,20,21,22,30},
-    py38-django{22,30},
-    pypy3-django{111,20,21,22},
+    py35-django{22},
+    py36-django{22,31},
+    py37-django{22,31},
+    py38-django{22,31},
+    pypy3-django{22,31},
 
 [gh-actions]
 python =
@@ -24,11 +24,8 @@ setenv =
     PYTHONPATH = {toxinidir}
 deps =
     -rtests/requirements.txt
-    django111: Django >=1.11, <2.0
-    django20: Django>=2.0,<2.1
-    django21: Django>=2.1,<2.2
     django22: Django>=2.2,<3
-    django30: Django>=3.0
+    django31: Django>=3.1,<3.2
 commands =
     pytest {posargs:tests}