Add Python 3.12

Author: fabaff

.github/workflows/python-app.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [ "3.9", "3.10", "3.11" ]
+        python-version: [ "3.10", "3.11", "3.12" ]
 
     steps:
     - uses: actions/checkout@v2