Update dependency livekit-client to v2.19.0 #1509

Job	Run time
Make RTC sdist	17s
Build RTC wheels (x86_64)	1m 1s
Build RTC wheels (AMD64)	1m 37s
Generating protobuf	22s
Build RTC wheels (x86_64 arm64)	1m 9s
Build RTC wheels (aarch64)	1m 32s
Test (ubuntu-latest, Python 3.14) / Test (ubuntu-latest, Python 3.14)	1m 32s
Test (windows-latest, Python 3.14) / Test (windows-latest, Python 3.14)	2m 4s
Test (ubuntu-latest, Python 3.11) / Test (ubuntu-latest, Python 3.11)	1m 55s
Test (macos-latest, Python 3.9) / Test (macos-latest, Python 3.9)	2m 41s
Test (ubuntu-latest, Python 3.12) / Test (ubuntu-latest, Python 3.12)	1m 41s
Test (ubuntu-latest, Python 3.9) / Test (ubuntu-latest, Python 3.9)	2m 1s
Test (windows-latest, Python 3.12) / Test (windows-latest, Python 3.12)	1m 56s
Test (macos-latest, Python 3.14) / Test (macos-latest, Python 3.14)	1m 56s
Test (ubuntu-latest, Python 3.10) / Test (ubuntu-latest, Python 3.10)	1m 33s
Test (windows-latest, Python 3.9) / Test (windows-latest, Python 3.9)	3m 10s
Test (ubuntu-latest, Python 3.13) / Test (ubuntu-latest, Python 3.13)	1m 33s
Test (macos-latest, Python 3.12) / Test (macos-latest, Python 3.12)	2m 8s
Publish RTC release	-1s
docs	0s
	30m 7s

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