Moving GUPnP-List to Discord

[Jens Georg <mail jensge org>]

Hello everyone,

This mailing list will be archived in favour of continued discussion at
GNOME's Discourse instance. No need to worry that this will mess with
your workflow: it is still possible to get notifications by email by
subscribing to the [gupnp] tag. You can also still reply by e-mail
if you prefer. Just like before, it's also possible to receive a
general weekly digest.

Finally, feel welcome to say hi by introducing yourself over at
https://discourse.gnome.org/t/say-hello-thread/ !