Merge branch 'no-extlinux' into 'master'

Don't try to run extlinux

See merge request Librem5/image-builder!157

build-image

@@ -279,6 +279,7 @@ sudo pureos_board="${pureos_board}" \
     --hostname='pureos' --user=purism/123456 --sudo \
     --customize "${cwd}/root.sh" \
     --owner "$(whoami)" \
+    --no-extlinux \
     "${custom_package_opt[@]}" \
     "${vmdebootstrap_opts[@]}" \
     ${NULL}