Add Django 3.1 and Python 3.9 support

Signed-off-by: Yohann D'ANELLO <ynerant@¢rans.org>
Signed-off-by: Yohann D'ANELLO <ynerant@crans.org>

tox.ini

@@ -9,9 +9,15 @@ envlist=
     py36-django22,
     py37-django22,
     py38-django22,
+    py39-django22,
     py36-django30,
     py37-django30,
     py38-django30,
+    py39-django30,
+    py36-django31,
+    py37-django31,
+    py38-django31,
+    py39-django31,
 
 [flake8]
 max-line-length=100
@@ -37,54 +43,12 @@ commands=
     {[post_cmd]commands}
 whitelist_externals={[post_cmd]whitelist_externals}
 
-[testenv:py27-django17]
-basepython=python2.7
-deps =
-    Django>=1.7,<1.8
-    {[base]deps}
-
-[testenv:py27-django18]
-basepython=python2.7
-deps =
-    Django>=1.8,<1.9
-    {[base]deps}
-
-[testenv:py27-django19]
-basepython=python2.7
-deps =
-    Django>=1.9,<1.10
-    {[base]deps}
-
-[testenv:py27-django110]
-basepython=python2.7
-deps =
-    Django>=1.10,<1.11
-    {[base]deps}
-
 [testenv:py27-django111]
 basepython=python2.7
 deps =
     Django>=1.11,<1.12
     {[base]deps}
 
-[testenv:py34-django17]
-basepython=python3.4
-deps =
-    Django>=1.7,<1.8
-    {[base]deps}
-
-[testenv:py34-django18]
-basepython=python3.4
-deps =
-    Django>=1.8,<1.9
-    {[base]deps}
-
-[testenv:py35-django110]
-basepython=python3.5
-deps =
-    Django>=1.10,<1.11
-    {[base]deps}
-
 [testenv:py35-django111]
 basepython=python3.5
 deps =
@@ -97,34 +61,10 @@ deps =
     Django>=1.11,<1.12
     {[base]deps}
 
-[testenv:py35-django20]
-basepython=python3.5
-deps =
-    Django>=2.0,<2.1
-    {[base]deps}
-
-[testenv:py36-django20]
-basepython=python3.6
-deps =
-    Django>=2.0,<2.1
-    {[base]deps}
-
-[testenv:py35-django21]
-basepython=python3.5
-deps =
-    Django>=2.1,<2.2
-    {[base]deps}
-
-[testenv:py36-django21]
-basepython=python3.6
-deps =
-    Django>=2.1,<2.2
-    {[base]deps}
-
-[testenv:py37-django21]
+[testenv:py37-django111]
 basepython=python3.7
 deps =
-    Django>=2.1,<2.2
+    Django>=1.11,<1.12
     {[base]deps}
 
 [testenv:py36-django22]
@@ -145,6 +85,12 @@ deps =
     Django>=2.2,<3.0
     {[base]deps}
 
+[testenv:py39-django22]
+basepython=python3.9
+deps =
+    Django>=2.2,<3.0
+    {[base]deps}
+
 [testenv:py36-django30]
 basepython=python3.6
 deps =
@@ -163,6 +109,36 @@ deps =
     Django>=3.0,<3.1
     {[base]deps}
 
+[testenv:py39-django30]
+basepython=python3.9
+deps =
+    Django>=3.0,<3.1
+    {[base]deps}
+
+[testenv:py36-django31]
+basepython=python3.6
+deps =
+    Django>=3.1,<3.2
+    {[base]deps}
+
+[testenv:py37-django31]
+basepython=python3.7
+deps =
+    Django>=3.1,<3.2
+    {[base]deps}
+
+[testenv:py38-django31]
+basepython=python3.8
+deps =
+    Django>=3.1,<3.2
+    {[base]deps}
+
+[testenv:py39-django31]
+basepython=python3.9
+deps =
+    Django>=3.1,<3.2
+    {[base]deps}
+
 
 [testenv:flake8]
 basepython=python3