Bug#911166: gtksourceview2: Do not release with Buster

[Yavor Doganov]

On Tue, Oct 16, 2018 at 12:49:36PM -0400, Jeremy Bicha wrote:
> Please port your package to gtk3 and gtksourceview4.

This is slightly confusing to me; there is src:gtksourceview3 but I
cannot find src:gtksourceview4.  It's not in the NEW queue either.  Is
it going to be a new source package?  If yes, when it is going to be
uploaded to Debian?  (I assume it is API/ABI incompatible with
gtksourceview3.)

Is porting from gtksourceview2 to gtksourceview3 desirable now or it
is preferred to wait for gtksourceview4?