Drop support for Python 3.5

It has reached its EOL in September 2020, see
https://www.python.org/dev/peps/pep-0478/#release-schedule

.github/workflows/test.yml

@@ -9,7 +9,7 @@ jobs:
       fail-fast: false
       max-parallel: 5
       matrix:
-        python-version: ['3.5', '3.6', '3.7', '3.8', 'pypy3']
+        python-version: ['3.6', '3.7', '3.8', 'pypy3']
 
     steps:
     - uses: actions/checkout@v2

docs/changes.rst

@@ -6,7 +6,7 @@ Changelog
 unreleased
 ^^^^^^^^^^
 
-- **BACKWARD INCOMPATIBLE** Drop support for Python 2.7.
+- **BACKWARD INCOMPATIBLE** Drop support for Python 2.7 and 3.5.
 
 - **BACKWARD INCOMPATIBLE** Drop support for Django < 2.2.
 

setup.py

@@ -52,7 +52,6 @@ setup(
         'License :: OSI Approved :: BSD License',
         'Operating System :: OS Independent',
         'Programming Language :: Python',
-        'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: 3.8',

tox.ini

@@ -5,12 +5,10 @@ minversion = 1.8
 whitelist_externals = sphinx-build
 envlist =
     py36-checkqa,
-    py{35,36,37,38,py3}-dj22
-    py{36,37,38,py3}-dj{30,master}
+    py{36,37,38,py3}-dj{22,30,master}
 
 [gh-actions]
 python =
-    3.5: py35
     3.6: py36,flake8,readme
     3.7: py37
     3.8: py38