vault: add error message for empty tarballs in python3.11+
Valentin's fix for iteration of empty tarballs in the tarfile stdlib module was merged and released in Python 3.11, so we need to handle that case properly.
Staging instance, all changes can be removed at any time
Valentin's fix for iteration of empty tarballs in the tarfile stdlib module was merged and released in Python 3.11, so we need to handle that case properly.