bump notebook-checks to python 3.12

.github/workflows/nbval.yaml

@@ -21,7 +21,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v2
       with:
-        python-version: "3.10"
+        python-version: "3.12"
     - name: Install notebook environment
       run: |
         python -m pip install --upgrade pip wheel