Builds an sdist, places it in sdist_directory

def build_sdist(sdist_directory, config_settings=None):
    """Builds an sdist, places it in sdist_directory"""
    poetry = Poetry.create(".")

    path = SdistBuilder(poetry, SystemEnv(Path(sys.prefix)), NullIO()).build(
        Path(sdist_directory)
    )

    return unicode(path.name)