feat: add a *suspense* sound when waiting for buzz

[diogogmatos]

On the game, when someone select a category and the host finishes reading the question, there is no sound whatsoever in the period between finishing reading the question and waiting for a participant to press the BUZZ. If no ones wants to risk answering, there is a perpetual silence until the timer ends. A suspense sound, like a heartbeat or something, would make this period more engaging.

(To cook some cool sounds, talk to @cgustavop 👀)