Remove Django 3.1 support.

CHANGES.rst

@@ -9,3 +9,4 @@ Unreleased
 - Add Django 3.2 support.
 - Add Python 3.10 to testing matrix
 - Add Django 4.0 support.
+- Remove Django 3.1 support.

docs/source/installation.rst

@@ -14,7 +14,7 @@ The repository can be found at https://github.com/jazzband/django-auditlog/.
 - Python 3.7 or higher
 - Django 2.2 or higher
 
-Auditlog is currently tested with Python 3.7 - 3.8 and Django 2.2, 3.1 and 3.2. The latest test report can be found
+Auditlog is currently tested with Python 3.7+ and Django 2.2, 3.2 and 4.0. The latest test report can be found
 at https://github.com/jazzband/django-auditlog/actions.
 
 Adding Auditlog to your Django application

setup.py

@@ -32,7 +32,6 @@ setup(
         "Programming Language :: Python :: 3.10",
         "Framework :: Django",
         "Framework :: Django :: 2.2",
-        "Framework :: Django :: 3.1",
         "Framework :: Django :: 3.2",
         "License :: OSI Approved :: MIT License",
     ],

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 envlist =
-    {py37,py38,py39}-django{22,31}
+    {py37,py38,py39}-django22
     {py37,py38,py39,py10}-django32
     {py38,py39,py10}-djangomain
     py38-docs
@@ -12,7 +12,6 @@ commands =
     coverage xml
 deps =
     django22: Django>=2.2,<2.3
-    django31: Django>=3.1,<3.2
     django32: Django>=3.2,<3.3
     djangomain: https://github.com/django/django/archive/main.tar.gz
     # Test requirements