workflows/pytest: add Python 3.12

Author: miltondp

.github/workflows/pytest.yaml

@@ -17,7 +17,7 @@ jobs:
       max-parallel: 4
       fail-fast: false
       matrix:
-        python-version: ["3.10", "3.11"]
+        python-version: ["3.10", "3.11", "3.12"]
         os: [ubuntu-latest, macOS-latest, windows-latest]
     steps:
       - name: Checkout git repo