Update tox.ini

Convert build matrix from py-dj to dj-py

tox.ini

@@ -4,18 +4,12 @@ envlist =
     fmt, lint, mypy,
     django-checks,
     ; https://docs.djangoproject.com/en/5.0/releases/
-    ;      | 3.2 | 4.2 | 5.0 | main
-    ; ---  | --- | --- | --- | ---
-    ; 3.8  | x   | x   | -   | -
-    ; 3.9  | x   | x   | -   | -
-    ; 3.10 | x   | x   | x   | x
-    ; 3.11 | -   | x   | x   | x
-    ; 3.12 | -   | -   | x   | x
-    py38-django{32,40,41,42}
-    py39-django{32,40,41,42}
-    py310-django{32,40,41,42,50,main}
-    py311-django{32,40,41,42,50,main}
-    py312-django{32,40,41,42,50,main}
+    django32-py{38,39,310}
+    django40-py{38,39,310}
+    django41-py{38,39,310,311}
+    django42-py{38,39,310,311}
+    django50-py{310,311,312}
+    djangmain-py{311,312}
 
 [testenv]
 deps =