typo in tests

fixed typos in the python versions listed in tests

Author: spcarte

.github/workflows/tests.yml

@@ -12,7 +12,7 @@ jobs:
 
     strategy:
       matrix:
-        python-version: [3.9, 3.10, 3.11]
+        python-version: ['3.9', '3.10', '3.11']
 
     steps:
       - name: Checkout repository