Added Django 3.1 test environment.

Signed-off-by: Hasan Ramezani <hasan.r67@gmail.com>

.travis.yml

@@ -9,6 +9,7 @@ python:
 env:
   - DJANGO=2.2
   - DJANGO=3.0
+  - DJANGO=3.1
   - DJANGO=master
 jobs:
   fast_finish: true

setup.py

@@ -46,6 +46,7 @@ setup(
         "Framework :: Django",
         "Framework :: Django :: 2.2",
         "Framework :: Django :: 3.0",
+        "Framework :: Django :: 3.1",
         "Intended Audience :: Developers",
         "Intended Audience :: System Administrators",
         "License :: OSI Approved :: MIT License",

tox.ini

@@ -1,7 +1,7 @@
 [tox]
 envlist =
     qa
-    py{36,37,38,py3}-django{22,30,master}
+    py{36,37,38,py3}-django{22,30,31,master}
 
 [travis]
 python =
@@ -14,6 +14,7 @@ python =
 DJANGO =
     2.2: django22
     3.0: django30
+    3.1: django31
     master: djangomaster
 
 [testenv]
@@ -21,6 +22,7 @@ deps =
     -r requirements.txt
     django22: django>=2.2,<2.3
     django30: django>=3.0,<3.1
+    django31: django>=3.1,<3.2
     djangomaster: https://github.com/django/django/archive/master.tar.gz
 usedevelop = True
 commands =