Add django<4 constraint to workflow

.github/workflows/pythonpackage.yml

@@ -19,7 +19,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install -r requirements.txt -r requirements-testing.txt
+        pip install -r requirements.txt -r requirements-testing.txt -c constraints-Django32.txt
     # - name: Lint with flake8
     #   run: |
         # pip install flake8