try with both

setup.py

@@ -14,7 +14,7 @@ setup(
                       'swiftspec @ git+https://github.com/fsspec/swiftspec',
                       'python-swiftclient>=3.10.0',
                       'pytest'],
-#		      'lxml'],
+ 		      'lxml', 'libxslt'],
     url='???',
     author='Fabian Wachsmann, Marco Kulüke',
     author_email='wachsmann@dkrz.de'