Check that intended python version is being used

Author: dandavison

.github/workflows/ci.yml

@@ -49,6 +49,14 @@ jobs:
       - uses: astral-sh/setup-uv@v5
       - run: uv tool install poethepoet
       - run: uv sync --all-extras
+      - name: Check python version
+        shell: bash
+        run: |
+          actual=$(python -c "import sys; print('.'.join(map(str, sys.version_info[:2])))")
+          if [[ "$actual" != "${{ matrix.python }}" ]]; then
+            echo "Python version in use ($actual) does not match intended version (${{ matrix.python }})"
+            exit 1
+          fi
       - run: poe bridge-lint
         if: ${{ matrix.clippyLinter }}
       - run: poe lint