Fix testing workflow

Author: sjavis

.github/workflows/testing.yaml

@@ -16,7 +16,7 @@ jobs:
 
     strategy:
       matrix:
-        python-version: [3.10, 3.11, 3.12]
+        python-version: ['3.10', '3.11', '3.12']
 
     steps:
       - uses: actions/checkout@v4