Update ci.yml

Author: tschm

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       matrix:
         os: [ ubuntu-latest, windows-latest, macos-latest ]
-        python-version: ['3.10', '3.11' ]
+        python-version: ['3.9', '3.10', '3.11', '3.12' ]
 
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps: