Add testing for Python 3.9 (#218)

Author: kujyp

.github/workflows/main.yml

@@ -10,7 +10,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python: ["3.5", "3.6", "3.7", "3.8"]
+        python: ["3.5", "3.6", "3.7", "3.8", "3.9"]
         os: [ubuntu-latest, windows-latest]
         include:
           - python: "3.5"
@@ -21,11 +21,13 @@ jobs:
             tox_env: "py37"
           - python: "3.8"
             tox_env: "py38"
+          - python: "3.9"
+            tox_env: "py39"
 
     steps:
     - uses: actions/checkout@v1
     - name: Set up Python
-      uses: actions/setup-python@v1
+      uses: actions/setup-python@v2
       with:
         python-version: ${{ matrix.python }}
     - name: Install tox

setup.py

@@ -32,6 +32,7 @@
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
         "Programming Language :: Python :: 3 :: Only",
         "Topic :: Software Development :: Testing",
     ],

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 minversion = 3.5.3
-envlist = py{35,36,37,38}, linting, norewrite
+envlist = py{35,36,37,38,39}, linting, norewrite
 
 [testenv]
 passenv = USER USERNAME