changing python version to 3.9 for github workflow

Author: mirochaj

.github/workflows/test_suite.yaml

@@ -16,7 +16,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [3.8]
+        python-version: [3.9]
 
     steps:
     - uses: actions/checkout@v2