Use a compatible CPython with Pyodide

Author: Kodiologist

.github/workflows/tests.yaml

@@ -40,7 +40,7 @@ jobs:
           python-version: ${{ matrix.python }}
     - if: matrix.python == 'pyodide'
       uses: actions/setup-python@v5
-      with: {python-version: 3}
+      with: {python-version: 3.12}
     - if: matrix.python == 'pyodide'
       uses: actions/setup-node@v4
     - name: Install