ci(github-action): update lowest tested python version to 3.6.10

Github action does not have 3.6.1

Author: Lee-W

.github/workflows/pythonpackage.yml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       max-parallel: 4
       matrix:
-        python-version: [3.6, 3.7, 3.8]
+        python-version: [3.6.10, 3.7, 3.8]
 
     steps:
     - uses: actions/checkout@v2