Add Python 3.13 to linting workflow

Author: petri

.github/workflows/test-lint.yaml

@@ -16,10 +16,10 @@ jobs:
     strategy:
       matrix:
         python-version:
-          - '3.9'
           - '3.10'
           - '3.11'
           - '3.12'
+          - '3.13'
 
     steps:
       - name: Checkout code