Remove python 3.5 and 3.6 from testing, add 3.9, 3.10

Author: coldfix

.github/workflows/python-package.yml

@@ -11,10 +11,10 @@ jobs:
       matrix:
         os: [ubuntu-latest, windows-latest]
         python:
-          - "3.5"
-          - "3.6"
           - "3.7"
           - "3.8"
+          - "3.9"
+          - "3.10"
     defaults:
       run:
         shell: bash