gh-91217: deprecate xdrlib

[brettcannon]

Automerge-Triggered-By: GH:brettcannon

[miss-islington]

@brettcannon: Status check is done, and it's a success ✅ .

[megies]

@brettcannon we have some I/O routine over at obspy that uses xdrlib. Would it be a problem to just copy xdrlib.py into our codebase, which we release under LGPLv3?
I quickly rewrote the functionality we use, but I'd actually feel more comfortable to just copy this file and keep using it given that it has been around a long time and I would trust it far more than a quick rewrite, because I know not everything will be fully tested on the rewrite.

If you're the wrong person to ask.. would you know who to ask?

[brettcannon]

@megies IANAL, but from my understanding if you copy the code and keep the license with it then you're fine as the Python license is GPL-compatible.