Test with python 3.9

Author: einarf

.github/workflows/pythonpackage.yml

@@ -8,7 +8,7 @@ jobs:
  runs-on: ubuntu-latest
  strategy:
  matrix:
- python-version: [3.5, 3.6, 3.7, 3.8]
+ python-version: [3.5, 3.6, 3.7, 3.8, 3.9]
 
  steps:
  - uses: actions/checkout@v2