Reenable Python 3.8+ tests (#330)

Author: Dreamsorcerer

.github/workflows/ci.yml

@@ -57,7 +57,7 @@ jobs:
     needs: lint
     strategy:
       matrix:
-        pyver: [3.6, 3.7]
+        pyver: [3.6, 3.7, 3.8, 3.9]
         os: [ubuntu, macos]
         #include:
         #  - pyver: pypy3