fix github actions

Author: Linusp

.github/workflows/pythonpackage.yml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       max-parallel: 4
       matrix:
-        python-version: [2.7, 3.5, 3.6, 3.7]
+        python-version: [3.x]
 
     steps:
     - uses: actions/checkout@v1