Bug#940718: xml-core: please remove versioned depends on sed

Hi Andrej,

> xml-core depends on sed (>=3D 4.1.2-8). However, looking at sed, I don=E2=
=80=99t
> see the reason why this particular version, and it=E2=80=99s not even in
> oldoldstable anymore anyway. Please consider dropping the versioned
> requirement and replacing it with a plain one.

Just FYI this specific version was fixing #248910.
I agree this can be removed as this condition is supported by all the
debian versions we have,
However I need to do a bit of digging on whether we need to have sed
as a dependency at all. It looks like this dependency wouldn't be
needed anymore after #687109 but I'll need to do some testing to
confirm.

Thanks,
Joseph