test: setup tox

tox.ini

@@ -0,0 +1,26 @@
+[tox]
+isolated_build = true
+requires =
+    tox>=4.2
+env_list =
+    py312-django{50,42}
+    py311-django{50,42,41}
+    py310-django{50,42,41,40,32}
+    py39-django{42,41,40,32}
+    py38-django{42,41,40,32}
+
+[testenv]
+deps =
+    # Avoid duplicate test deps with Poetry deps
+    pytest
+    pytest-cov
+    pytest-django
+    # All supported Django versions
+    django50: Django>=5.0a1,<5.1
+    django42: Django>=4.2,<5.0
+    django41: Django>=4.1,<4.2
+    django40: Django>=4.0,<4.1
+    django32: Django>=3.2,<4.0
+commands =
+    python \
+      -m pytest {posargs:tests}