test on all python versions

Author: dnth

.github/workflows/run_tests.yml

@@ -16,7 +16,7 @@ jobs:
         fail-fast: false
         matrix:
             os: [ubuntu-22.04] # windows-2022 macos-13
-            python: ['3.8','3.10']
+            python: ['3.7', '3.8', '3.9','3.10']
       steps:
         - name: Checkout code
           uses: actions/checkout@v3