More readable names in the Tox matrix definition

tox.ini

@@ -1,9 +1,9 @@
 [tox]
 envlist =
-    py35-{22}
-    py36-{30,31,32}
-    py38-{30,31,32,40}
-    py310-{30,31,32,40}
+    py35-{dj22}
+    py36-{dj30,dj31,dj32}
+    py38-{dj30,dj31,dj32,dj40}
+    py310-{dj30,dj31,dj32,dj40}
 
 [gh-actions]
 python =
@@ -17,11 +17,11 @@ usedevelop = true
 deps =
     selenium
     coverage
-    22: Django >= 2.2, < 3.0
-    30: Django >= 3.0, < 3.1
-    31: Django >= 3.1, < 3.2
-    32: Django >= 3.2, < 4.0
-    40: Django >= 4.0, < 4.1
+    dj22: Django >= 2.2, < 3.0
+    dj30: Django >= 3.0, < 3.1
+    dj31: Django >= 3.1, < 3.2
+    dj32: Django >= 3.2, < 4.0
+    dj40: Django >= 4.0, < 4.1
 commands =
     python example/manage.py collectstatic --noinput -v 0
     coverage run -p example/manage.py test example -v 3