build: ppc64 is not publishing #14

ppc64 did not publish on 2026-10-16: no mirror in rootfs/ppc64/etc/pacman.d/mirrorlist served its database to a GitHub runner. The port is not built until one does, and nothing here needs to change for it to come back.

The multi architecture index keeps carrying the last image published for it, so latest still serves ppc64.

Last checked: https://github.com/pkgforge-dev/docker-archlinux/actions/runs/38884226329

This issue closes itself on the first run that publishes ppc64 again.