Debian package dependency doesn't garuantee working avahi solution

[z0rc]

Checklist:

• [x] I have checked that there are no issues with similar or the same content

  YOU SHOULD CHECK CLOSED ISSUES ASWELL

• [x] I have checked the FAQ (https://github.com/MarshallOfSound/Google-Play-Music-Desktop-Player-UNOFFICIAL-/wiki/FAQ) and the answer I am looking for is not there
• [x] I have double checked and can reproduce the issue

OS: Kubuntu 18.04

GPMDP Version: 4.6.1

Issue Descriptions: Avahi isn't usable despite avahi-daemon dependency

Steps to Reproduce: Install GPMPD on fresh Ubuntu, start via console, observe:

error: Failed to load bonjour with error: {}
Bonjour is required to use Chromecast Support or to enable ZeroConf for the PlaybackAPI
On linux you need to install "avahi"

Basically GPMDP requires old compatibility layer to be present, as it doesn't use native Avahi API. In order to properly enable avahi support user has to install libavahi-compat-libdnssd1.

So, I believe the proper fix will be adding mentioned package to dependency list.

Also while we're at it, again I'm asking to reconsider decision about making avahi-daemon as hard dependency and downgrade it to Recommends. Per Debian Policy:

Recommends

This declares a strong, but not absolute, dependency.

The Recommends field should list packages that would be found together with this one in all but unusual installations.

Avahi/Chromecast case fits perfectly into this definition.

[frankbaele]

Same problem on fedora 27, had to install the following package avahi-compat-libdns_sd to make it work .

[kkavchakHT]

I also had to install libavahi-compat-libdnssd1 on Kubuntu 18.10