Update pacman.conf to pacman-6.0.0-2
As suggested by xatier on GitHub: * https://github.com/archlinux/archlinux-docker/pull/41 * https://github.com/archlinux/archlinux-docker/pull/42/files
As suggested by xatier on GitHub: * https://github.com/archlinux/archlinux-docker/pull/41 * https://github.com/archlinux/archlinux-docker/pull/42/files