nixos/music-assistant: wait for network-online.target

This is required because the server fails to start when it cannot find
a route to send out mDNS packets.

Changed files
+3
nixos
modules
services
+3
nixos/modules/services/audio/music-assistant.nix
···
description = "Music Assistant";
documentation = [ "https://music-assistant.io" ];
+
after = [ "network-online.target" ];
+
wants = [ "network-online.target" ];
+
wantedBy = [ "multi-user.target" ];
environment = {