Add missed configuration file for readthedocs

.github/workflows/docs.yml

@@ -23,10 +23,10 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v2.3.4
 
-      - name: Set up Python 3.9
+      - name: Set up Python 3.8
         uses: actions/setup-python@v2.2.2
         with:
-          python-version: '3.9'
+          python-version: '3.8'
 
       - name: Install dependencies
         run: |

.readthedocs.yaml

@@ -0,0 +1,20 @@
+# This file is part of the django-environ.
+#
+# Copyright (c) 2021, Serghei Iakovlev <egrep@protonmail.ch>
+# Copyright (c) 2013-2021, Daniele Faraglia <daniele.faraglia@gmail.com>
+#
+# For the full copyright and license information, please view
+# the LICENSE.txt file that was distributed with this source code.
+
+---
+version: 2
+python:
+  # Keep version in sync with tox.ini (testenv:docs) and
+  # docs.yml (GitHub Action Workflow).
+  version: '3.8'
+
+  install:
+    - method: pip
+      path: .
+      extra_requirements:
+        - docs

tox.ini

@@ -71,6 +71,9 @@ commands = flake8 environ setup.py
 
 [testenv:docs]
 description = Build package documentation (HTML)
+# Keep basepython in sync with .readthedocs.yml and docs.yml
+# (GitHub Action Workflow).
+basepython = python3.8
 extras = docs
 commands =
     sphinx-build -n -T -W -b html -d {envtmpdir}/doctrees docs docs/_build/html