Skip test-admin-deploy-uboot.sh on s390x

It fails on a porterbox. ostree hard-codes zipl to be used on s390x,
so it's reasonable that tests for other bootloaders might not work.

Bug: ostreedev/ostree#3086
Forwarded: no

Gbp-Pq: Topic debian
Gbp-Pq: Name Skip-test-admin-deploy-uboot.sh-on-s390x.patch

tests/test-admin-deploy-uboot.sh

@@ -20,6 +20,11 @@
 
 set -euo pipefail
 
+if [ "${DEB_HOST_ARCH-$(dpkg --print-architecture)}" = s390x ]; then
+  echo "1..0 # SKIP uBoot not supported on s390x"
+  exit 0
+fi
+
 . $(dirname $0)/libtest.sh
 
 # Exports OSTREE_SYSROOT so --sysroot not needed.