chore(linux): Exclude autopkg tests on s390x

We don't build the binaries on s390x so it doesn't make sense trying
to run the autopkg tests on s390x. This change imports the changes
made on Debian in pkg version 16.0.138-4.

Co-authored-by: Gunnar Hjalmarsson <gunnarhj@ubuntu.com>
(cherry picked from commit e4caf4d4)