add testing on py3

Author: Alonreznik

.github/workflows/run_uts_on_prs.yml

@@ -14,7 +14,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        python-version: [2.7.18, 3.6, 3.7, 3.8, 3.9, 3.10, 3.11]
+        python-version: [3.6, 3.7, 3.8, 3.9, 3.10, 3.11]
 
     steps:
     - name: Checkout code