update protocol for backchannel support #113

Job	Run time
Detect package	0s
Build RTC wheels (${{ matrix.archs }})	0s
Tag release	0s
Build API	0s
Build Protocol	0s
Publish livekit-api	-1s
Publish livekit-protocol	-1s
Publish livekit (RTC)	-1s
Build Protocol docs	-1s
Build API docs	-1s
Build RTC docs	-1s
Create release PR	-6s
Build RTC sdist	-9s
	-21s

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