Add 3.8 to the Python matrix.

Author: adamghill

.github/workflows/python.yml

@@ -6,7 +6,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.6, 3.7]
+        python-version: [3.6, 3.7, 3.8, 3.9]
 
     steps:
       - uses: actions/[email protected]