nixos/tests/boot-stage1: Add myself to maintainers

As @edolstra pointed out that the kernel module might be painful to
maintain. I strongly disagree because it's only a small module and it's
good to have such a canary in the tests no matter how the bootup process
looks like, so I'm going the masochistic route and try to maintain it.

If it *really* becomes too much maintenance burden, we can still drop or
disable kcanary.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>