Add missing package to s390x builder

Author: malbarbo

ci/docker/s390x-unknown-linux-gnu/Dockerfile

@@ -5,7 +5,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
         gcc libc6-dev \
         gcc-s390x-linux-gnu libc6-dev-s390x-cross \
         debian-archive-keyring debootstrap cpio \
-        qemu-user-static qemu-system-s390x \
+        qemu-user-binfmt qemu-user-static qemu-system-s390x \
         sshpass openssh-client
 
 COPY linux-image.sh /