upstream is in the process of renaming to `hickory-dns`.
a consequence of this is that the main binary has been renamed from
`trust-dns` to `hickory-dns` and the repository has been moved (though
for the time being the old repo is still usable on account that it
redirects to the new one).
see: <https://bluejekyll.github.io/blog/posts/announcing-hickory-dns/>
