Workaround pacstrap -K issue[1]

@dvzrv reported this issue (on IRC) when building locally over a year
ago (2023-07-18) and I created a issue at the time[1]. The CI pipeline
is suddenly affected by the issue, so kill the gpg-agent after running
pacstrap as a workaround.

[1] arch-install-scripts#56

build.sh

@@ -78,6 +78,8 @@ EOF
 
   # We use the hosts package cache
   pacstrap -c -C pacman.conf -K -M "${MOUNT}" base linux grub openssh sudo btrfs-progs dosfstools efibootmgr
+  # Workaround for https://gitlab.archlinux.org/archlinux/arch-install-scripts/-/issues/56
+  gpgconf --homedir "${MOUNT}/etc/pacman.d/gnupg" --kill gpg-agent
   cp mirrorlist "${MOUNT}/etc/pacman.d/"
 }