devel/poco-devel: Older than stable port, deprecate for removal

The devel version of poco is signficantly behind the stable devel/poco
which is regularly updated. There's no apparent benefit to having two
ports in this case. I'll mention to the maintainer that devel/poco is
currently unmaintained in case he wishes to take that over even though
ports fury has been handling that for a while.

PR: 204824