Add Django 3.1 release candidate to test matrix

.appveyor.yml

@@ -19,6 +19,8 @@ environment:
       TOXENV: "py36-django22"
     - PYTHON: "C:\\Python36"
       TOXENV: "py36-django30"
+    - PYTHON: "C:\\Python36"
+      TOXENV: "py36-django31"
     - PYTHON: "C:\\Python37"
       TOXENV: "py37-django20"
     - PYTHON: "C:\\Python37"
@@ -27,6 +29,8 @@ environment:
       TOXENV: "py37-django22"
     - PYTHON: "C:\\Python37"
       TOXENV: "py37-django30"
+    - PYTHON: "C:\\Python37"
+      TOXENV: "py37-django31"
     - PYTHON: "C:\\Python38"
       TOXENV: "py38-django20"
     - PYTHON: "C:\\Python38"
@@ -35,6 +39,8 @@ environment:
       TOXENV: "py38-django22"
     - PYTHON: "C:\\Python38"
       TOXENV: "py38-django30"
+    - PYTHON: "C:\\Python38"
+      TOXENV: "py38-django31"
 matrix:
   fast_finish: true
 install:

.travis.yml

@@ -32,6 +32,8 @@ matrix:
       python: 3.6
     - env: TOXENV=py36-django30
       python: 3.6
+    - env: TOXENV=py36-django31
+      python: 3.6
     - env: TOXENV=py36-master
       python: 3.6
     - env: TOXENV=py37-django20
@@ -42,6 +44,8 @@ matrix:
       python: 3.7
     - env: TOXENV=py37-django30
       python: 3.7
+    - env: TOXENV=py37-django31
+      python: 3.7
     - env: TOXENV=py37-master
       python: 3.7
     - env: TOXENV=py38-django20
@@ -52,6 +56,8 @@ matrix:
       python: 3.8
     - env: TOXENV=py38-django30
       python: 3.8
+    - env: TOXENV=py38-django31
+      python: 3.8
     - env: TOXENV=py38-master
       python: 3.8
 script: tox -v

tox.ini

@@ -6,6 +6,7 @@ envlist =
   py{35,36,37,py3}-django21,
   py{35,36,37,py3}-django22,
   py{36,37,38,py3}-django30,
+  py{36,37,38,py3}-django31,
   py{36,37,38,py3}-master,
 
 [testenv]
@@ -23,6 +24,7 @@ deps =
   django21: Django>=2.1,<2.2
   django22: Django>=2.2,<3.0
   django30: Django>=3.0,<3.1
+  django31: Django==3.1rc1
   master: https://github.com/django/django/archive/master.tar.gz
 extras =
   brotli