PBS 4 Upgrade PVE
This script guides you through upgrading Proxmox Backup Server from version 3.x (Debian 12 Bookworm) to version 4.0 (Debian 13 Trixie). It adjusts the Debian base sources, configures PBS 4 repositories in deb822 format, updates enterprise/no-subscription/test repos, runs a full system upgrade, and finalizes with a reboot.