deb frr dependency 10.4.1

[Christoph]

> We need to do some lobbying both upstream (FRR) and downstream (Debian)
> so that they enable out-of-tree plugin support.

thanks for your explanation!

> In the meantime, we could work on packaging an FRR DEB package for grout
> usage.

that would be great and we would be happy testers if we manage to get a 
working setup :)

And yes we are fine with any 10.5+ frr branch.

best regards,
Christoph