Release 2.0.0b19, beta quality, for testing only

borgbackup 2.0.0b19 beta release - do not use this on production backup repositories.

Long changelog:
https://borgbackup.readthedocs.io/en/2.0.0b19/changes.html#version-2-0-0b19-2025-07-02

If you use pip to install this, use: pip install "borgbackup==2.0.0b19"

Docs: https://borgbackup.readthedocs.io/en/2.0.0b19/

Discussion: #8973

Notes:

• The macOS Intel binaries will come later.
• Give feedback if you find the linux32 (32bit intel/amd) binary useful.
• The release notes erroneously state 2025-07-02 as release date, but it actually was 2025-08-02.