Remove references to ``passlib`` in docs

[Eclips4]

Our crypt documentation recommends using passlib instead of the removed crypt library.
It seems that passlib has been unsupported for at least five years. I'm not sure whether the project is officially deprecated, but this is at least concerning.

More importantly, passlib appears to rely on the now-removed crypt module: issue.

I propose removing the reference to passlib.

Linked PRs

• gh-139672: Remove references topasslib #139673