bump to Python 3.10

Author: boegel

.github/workflows/deploy.yml

@@ -15,7 +15,7 @@ jobs:
     - name: set up Python
       uses: actions/setup-python@v1
       with:
-        python-version: 3.9
+        python-version: '3.10'
 
     - name: install mkdocs
       run: |