Add Django3 to test matrix and setup.py metadata

setup.py

@@ -54,6 +54,7 @@ setup(
         "Framework :: Django :: 2.0",
         "Framework :: Django :: 2.1",
         "Framework :: Django :: 2.2",
+        "Framework :: Django :: 3.0",
         "Programming Language :: Python",
         "Programming Language :: Python :: 2",
         "Programming Language :: Python :: 2.7",

tox.ini

@@ -2,6 +2,7 @@
 envlist =
     py27-django111
     py{35,36,37,38}-django{111,20,21,22}
+    py{36,37,38}-django{30}
     lint
 
 [testenv]
@@ -13,6 +14,7 @@ deps =
     django20: django>=2.0,<2.1
     django21: django>=2.1,<2.2
     django22: django>=2.2,<2.3
+    django30: django>=3.0,<3.1
     appdirs==1.4.3
     py27: mock==2.0.0