Remove get_password_hash, unused

[stefanor]

spwd is removed in Python 3.13. But fortunately, this function itself is never used.

Part of: #1073

[moreati]

refs #1073

[moreati]

Notes

• spwd.getspnam(name) requires root (or mumble POSIX capability). It reads /etc/shadow. There's no interaction with any stdio or a tty
• getpass.getpass(prompt='Password: ', stream=None) requires no additional privilege. It writes to stream if supplied, or the controlling terminal if available, or stderr otherwise. It reads from stream if provided (I think), or the controlling tty, or stdin (with a warning).

[moreati]

This is just example code that is never called by anything.

Doubly so, get_password() (prev. get_password_hash()) isn't even called within its own example script.

[stefanor]

Let's delete it. I was assuming it was there as a demonstrative example.