Fix for #243 (deprecations in GObject) - #244

This is resolving

[soundplay_node.py-1] /opt/ros/humble/lib/sound_play/soundplay_node.py:215: PyGIDeprecationWarning: Since version 3.11, calling threads_init is no longer needed. See: https://wiki.gnome.org/PyGObject/Threading
[soundplay_node.py-1]   GObject.threads_init()
[soundplay_node.py-1] /opt/ros/humble/lib/sound_play/soundplay_node.py:216: PyGIDeprecationWarning: GObject.MainLoop is deprecated; use GLib.MainLoop instead

@knorth55 Could you check this please ?

@tomkimsour
this PR is targeted to master branch (ROS1 branch), so I will not merge this PR.
if you want to remove the deprecation warning, you can open a similar PR to ROS2 branch.

This PR just remove warning and does not implement new feature nor fix a bug, so I'm not super open to merge this.
This kind of PR is correct, but, at the same time, it may drop backward compatibility.

But if you think the warning message is too annoying, I can merge the change.