Try this

Author: Cadair

.github/workflows/test_and_publish.yml

@@ -40,6 +40,6 @@ jobs:
     needs: [test]
     uses: OpenAstronomy/github-actions-workflows/.github/workflows/publish_pure_python.yml@v1
     with:
-      test_command: pytest tests; pytest tests --mpl
+      test_command: pytest ../pytest-mpl/pytest-mpl/tests
     secrets:
       pypi_token: ${{ secrets.pypi_password }}