Update test environments

setup.py

@@ -45,5 +45,5 @@ setup(
     },
     keywords=["django", "openid", "sso"],
     python_requires=">=3.6",
-    install_requires=["mozilla-django-oidc>=1.2.3,<2"],
+    install_requires=["mozilla-django-oidc>=1.2.3,<2", "python-ldap>=3.2.0,<4"],
 )

tox.ini

 [tox]
 envlist =
-    py{36,37,38}-django300
+    py{36,37,38}-django{30,22}
 
 [testenv]
 deps =
     -r{toxinidir}/tests/requirements.txt
-    django300: Django>=3.0.0,<3.1
+    django30: Django>=3.0,<3.1
+    django22: Django>=2.2,<3
 setenv =
     PYTHONPATH = {toxinidir}
     PYTHONUNBUFFERED = yes