SPEC0/NEP29: Add Python 3.12, drop Python 3.9

Author: dwhswenson

.github/workflows/test-suite.yml

@@ -24,12 +24,12 @@ jobs:
     strategy:
       matrix:
         CONDA_PY:
+          - "3.12"
           - "3.11"
           - "3.10"
-          - "3.9"
         INTEGRATIONS: [""]
         include:
-          - CONDA_PY: "3.11"
+          - CONDA_PY: "3.12"
             INTEGRATIONS: 'all-optionals'
 
     steps: