add setup python to workflow

Author: alistairewj

.github/workflows/psql.yml

@@ -28,6 +28,11 @@ jobs:
       - name: Check out repository code
         uses: actions/checkout@v3
 
+      - name: Install Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.10' 
+
       - name: Download demo data
         uses: ./.github/actions/download-demo