Test with python 3.7 - 3.9

.github/workflows/pythonapp.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       max-parallel: 2
       matrix:
-        python-version: [3.8, 3.7, 3.6]
+        python-version: [3.9, 3.8, 3.7]
     steps:
     - uses: actions/checkout@v1
     - name: 'Set up Python ${{ matrix.python-version }}'

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 isolated_build = True
-envlist = py38,py37,py36
+envlist = py39,py38,py37
 skip_missing_interpreters = True
 
 [testenv]