Bug#885813: bumping severity of xfce4-notes-plugin's use of libunique to Serious

[Jeremy Bicha <jbicha@debian.org>]

Control: severity -1 serious

The Debian GNOME team would like to remove libunique from Debian.
Therefore, I'm bumping the severity of this bug to serious.

Please see the master bug https://bugs.debian.org/895520 for
documentation on moving away from libunique. It looks like it requires
finishing the port to gtk3.

Because xfce4-notes-plugin is a "key package", it won't be
automatically removed from Testing. But note that this package is one
of the last 2 or 3 keeping libunique in Debian.

Thanks,
Jeremy Bicha