Fix mute status on Big Sur

[aaronkollasch]

Hey Andrew,

Your btt automation services have worked really well for me, so thanks for making them available.

I recently switched to Big Sur and found that while the volume was reflected in the control strip icon, mute status was always True.

It seems that AudioHardwareServiceGetPropertyData (and AudioObjectGetPropertyData) need a uint32 rather than a bool (test script in swift), and a couple lines fixed the issue.

This change may not be backwards compatible but I'm posting it just in case anyone else has the same issue.

Aaron