Add Django 4.2 compat' and update test dependencies.

tox.ini

@@ -3,6 +3,7 @@ envlist =
     py{37,38,39,310}-django32
     py{38,39,310}-django40
     py{38,39,310,311}-django41
+    py{38,39,310,311}-django42
     lint
     coverage
 
@@ -15,6 +16,7 @@ python =
     3.11: py311
 
 [testenv]
+allowlist_externals = ./manage.py
 commands = ./manage.py test --no-input {posargs}
 extras = test
 pip_pre = true
@@ -23,9 +25,10 @@ deps =
     django32: django>=3.2,<3.3
     django40: django>=4.0,<4.1
     django41: django>=4.1,<4.2
+    django42: django>=4.2,<4.3
 
 [testenv:lint]
-basepython = python3.10
+basepython = python3.11
 deps = pre-commit
 commands = pre-commit run --all-files --show-diff-on-failure