Adds PYTHONPATH and version diagnostics in CI

Author: AndrewSazonov

.github/workflows/test.yaml

@@ -204,6 +204,9 @@ jobs:
           for env in ${{ env.PIXI_ENVS }}; do
             echo "🔹🔸🔹🔸🔹   Current env: $env   🔹🔸🔹🔸🔹"
             pixi run --environment $env wheel
+            echo "PYTHONPATH:"
+            pixi run printenv PYTHONPATH || true
+            pixi run --environment $env easydiffraction --version
           done
 
       - name: Add easydiffraction package from the built wheel