run tests on python 3.9 and 3.10

Author: josiasmontag

.github/workflows/run-tests.yml

@@ -13,7 +13,7 @@ jobs:
 
     strategy:
       matrix:
-        python-version: ['2.7', '3.6', '3.7', '3.8']
+        python-version: ['2.7', '3.6', '3.7', '3.8', '3.9', '3.10']
 
     steps:
     - uses: actions/checkout@v2