Bug#704603: gnome-core: No alternative dependency to allow removing pulseaudio in gnome-core

[Nicolas Le Cam]

Now that PipeWire is around the corner in testing/unstable and
becoming a viable alternative it could be set as one.

At the moment we can't follow PipeWire wiki instructions
(https://wiki.debian.org/PipeWire#Debian_Testing.2FUnstable) to remove
package pulseaudio-module-bluetooth as it is a hard dependency of
gnome-core.

Regards,
Nicolas Le Cam