switch to python3.9 for tests

Author: wpoely86

.github/workflows/testpatterns.yml

@@ -6,7 +6,7 @@ jobs:
       runs-on: ubuntu-latest
       strategy:
         matrix:
-          python-version: [2.7, 3.6]
+          python-version: 3.9
       steps:
       - name: add logstash repo
         uses: myci-actions/add-deb-repo@4