test: drop test for python 3.5

Author: juvenn

.github/workflows/pythonpackage.yml

@@ -43,7 +43,7 @@ jobs:
     strategy:
       max-parallel: 1
       matrix:
-        python-version: [3.5, 3.9, "3.10"]
+        python-version: [3.6, 3.9, "3.10"]
     steps:
     - uses: actions/checkout@v2
     - name: Set up Python