CI: mkosi: Fix mainline boot on Ubuntu mantic #290

Job	Run time
build (centos:7, yum install -y kernel-devel kernel gcc make elfutils-libelf-devel)	1m 45s
build (almalinux:8, yum install -y kernel-devel kernel gcc make elfutils-libelf-devel)	1m 58s
build (rockylinux:8, yum install -y kernel-devel kernel gcc make elfutils-libelf-devel)	2m 34s
build (quay.io/centos/centos:stream8, dnf install -y kernel-devel kernel gcc make elfutils-libelf...	2m 44s
build (quay.io/centos/centos:stream9, dnf install -y --nobest kernel-devel-matched gcc make)	2m 35s
build (fedora:latest, dnf install -y kernel-devel kernel gcc make elfutils-libelf-devel)	3m 34s
build (alt:sisyphus, apt-get update; apt-get install -y kernel-headers-modules-un-def gcc make li...	1m 22s
build (registry.opensuse.org/opensuse/tumbleweed, zypper -n install -y gcc make kernel-default-de...	1m 24s
build (registry.opensuse.org/opensuse/leap, zypper -n install -y gcc make kernel-default-devel ta...	1m 34s
	19m 30s

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