archivers/py-borgbackup: Update to 1.1.0

Shortened changelog of major features only:
https://www.borgbackup.org/releases/borg-1.1.html

Long changelog:
https://github.com/borgbackup/borg/blob/1.1.0/docs/changes.rst#version-110-2017-10-07

PR: 223135
Submitted by: jjuanino@gmail.com (maintainer)