Do not build extra subpackages
    
    Those subpackages requires bunch of optional
    dependencies [1] which we don't need for now.
    So I exclude them from building.
    
    [1]
    https://github.com/python-jsonschema/jsonschema/blob/main/pyproject.toml#L45-L65
    
    Related-to: https://review.rdoproject.org/r/q/If4874838500045fb13e05829b5d88371fa128a06