Bug#1090261: pristine-lfs test fail in Python 3.13

[Rebecca N. Palmer]

Control: tags -1 patch

Using Path() as a context manager hasn't done anything since Python 3.9, 
and is removed in 3.13:
https://docs.python.org/3/whatsnew/3.13.html#id4
Path.glob('**') now includes files as well as directories:
https://docs.python.org/3/whatsnew/3.13.html#pathlib

Fix:
https://salsa.debian.org/pristine-lfs-team/pristine-lfs/-/merge_requests/12
(which is the upstream repository - it was sent only there because the 
Debian repository is out of date)