py-borgbackup: updated to 1.2.8

Version 1.2.8 (2024-03-29)

For upgrade and compatibility hints, please also read the section "Upgrade Notes"
above.

Fixes:

- check: fix return code and log level for index entry value discrepancies
- with-lock: catch FileNotFoundError exception, print error msg
- benchmark: inherit options --rsh --remote-path
- fix Ctrl-C / SIGINT behaviour for pyinstaller-made binaries

New features:

- upgrade --check-tam: check manifest TAM auth,
  exit with rc=1 if there are issues.
- upgrade --check-archives-tam: check archives TAM auth,
  exit with rc=1 if there are issues.

Other changes:

- allow msgpack 1.0.8 (this might fix memory leaks with Python 3.12)
- use the latest Cython 0.29.x
- vagrant:

  - use / build binaries with python 3.9.19
  - use generic/openbsd7 box
- docs:

  - simplify TAM-related upgrade docs using the new commands
  - improve docs for borg with-lock
  - add more infos borg check --repair recreating the shadow index
    to change log

(adam)