Pausing/resuming in mpv doesn't affect the SyncPlay group

[diniamo]

Describe the bug

Pausing in mpv causes a local pause, which means it won't sync to the SyncPlay group, and you have to manually press Resume local playback in Jellyfin to sync up again. Pausing in mpv should pause for the SyncPlay group as well.

To Reproduce
Steps to reproduce the behavior:

1. Start a SyncPlay group
2. Open a video in mpv
3. Pause in mpv

Expected behavior

The video should be paused and resumed for everyone at the same time, even if using mpv to control that.

Desktop (please complete the following information):

• OS: NixOS
• Version 2.8.0