Change to `cl-lib` to suppress Emacs 27 warning

[wtao137]

Maybe this can be changed into cl-lib so the startup warning package cl is deprecated can be suppressed. https://github.com/gregsexton/ob-ipython/blob/7147455230841744fb5b95dcbe03320313a77124/ob-ipython.el#L44

[maker2413]

This is also causing issues for me currently.