Merge pull request nest#3192 from heplesser/hike-macos-python

Hike Python version for macOS tests to 3.12

Author: terhorstd

.github/workflows/nestbuildmatrix.yml

@@ -758,7 +758,7 @@ jobs:
       - name: "Set up Python 3.x"
         uses: actions/setup-python@0a5c61591373683505ea898e09a3ea4f39ef2b9c # v5.0.0
         with:
-          python-version: 3.9
+          python-version: 3.12
 
       - name: "Install MacOS system dependencies"
         run: |