Use pyproject.toml to determing python version to use for test

Author: robtaylor

.github/workflows/main.yaml

@@ -19,6 +19,8 @@ jobs:
           fetch-depth: 0
       - name: Set up PDM
         uses: pdm-project/setup-pdm@v4
+        with: 
+          python-version: "3.10"
       - name: Install dependencies
         run: |
           pdm install