arch_boxes_sync: Pull the artifacts from GitLab's package registry

arch-boxes has decided to use GitLab's package registry instead of job artifacts[1].

[1] arch-boxes@d04c8274

roles/arch_boxes_sync/files/arch-boxes-sync.sh

@@ -69,8 +69,8 @@ done
 mv "${LATEST_VERSION}" "${ARCH_BOXES_PATH}/"
 ln -nsf "${LATEST_VERSION}" "${ARCH_BOXES_PATH}/latest"
 
-date +%s > "${LASTUPDATE_PATH}"
-
 echo "Removing old releases"
 cd "${ARCH_BOXES_PATH}"
 comm --output-delimiter="" -3 <({ ls | grep -v latest | sort -r | head -n "${MAX_RELEASES}"; echo latest; } | sort) <(ls | sort) | tr -d '\0' | xargs --no-run-if-empty rm -rvf
+
+date +%s > "${LASTUPDATE_PATH}"