Add support for Python 3.12

tox.ini

@@ -2,8 +2,8 @@
 envlist =
     py{37,38,39,310}-django32
     py{38,39,310}-django40
-    py{38,39,310,311}-django41
-    py{38,39,310,311}-django42
+    py{38,39,310,311,312}-django41
+    py{38,39,310,311,312}-django42
     lint
     coverage
 
@@ -14,6 +14,7 @@ python =
     3.9: py39
     3.10: py310
     3.11: py311
+    3.12: py312
 
 [testenv]
 allowlist_externals = ./manage.py