New bugfix release 2.54.2

New snapd release 2.54.2

See https://forum.snapcraft.io/t/the-snapd-roadmap/1973 for high-level overview.

• tests: exclude interfaces-kernel-module load on arm
• tests: ensure that test-snapd-kernel-module-load is removed
• tests: do not test microk8s-smoke on arm
• tests/core/failover: replace boot-state with snap debug boot-vars
• tests: use snap info|awk to extract tracking channel
• tests: fix remodel-kernel test when running on external devices
• .github/workflows/test.yaml: also check internal snapd version for cleanliness
• packaging/ubuntu-16.04/rules: eliminate seccomp modification
• bootloader/assets/grub_*cfg_asset.go: update Copyright
• build-aux/snap/snapcraft.yaml: adjust comment about get-version
• .github/workflows/test.yaml: add check in github actions for dirty snapd snaps
• build-aux/snap/snapcraft.yaml: use build-packages, don't fail dirty builds
• data/selinux: allow poking /proc/xen