fix: point rust-sdks to livekit-ffi/v0.12.56 (#662) #1407

Job	Run time
Make RTC sdist	20s
Build RTC wheels (x86_64 arm64)	1m 16s
Build RTC wheels (aarch64)	1m 24s
Build RTC wheels (AMD64)	1m 14s
Build RTC wheels (x86_64)	1m 14s
Generating protobuf	0s
Test (macos-latest, Python 3.14) / Test (macos-latest, Python 3.14)	49s
Test (ubuntu-latest, Python 3.9) / Test (ubuntu-latest, Python 3.9)	45s
Test (ubuntu-latest, Python 3.13) / Test (ubuntu-latest, Python 3.13)	39s
Test (macos-latest, Python 3.12) / Test (macos-latest, Python 3.12)	44s
Test (windows-latest, Python 3.9) / Test (windows-latest, Python 3.9)	1m 30s
Test (ubuntu-latest, Python 3.12) / Test (ubuntu-latest, Python 3.12)	29s
Test (ubuntu-latest, Python 3.11) / Test (ubuntu-latest, Python 3.11)	31s
Test (windows-latest, Python 3.14) / Test (windows-latest, Python 3.14)	1m 32s
Test (windows-latest, Python 3.12) / Test (windows-latest, Python 3.12)	1m 1s
Test (ubuntu-latest, Python 3.10) / Test (ubuntu-latest, Python 3.10)	28s
Test (macos-latest, Python 3.9) / Test (macos-latest, Python 3.9)	1m 2s
Test (ubuntu-latest, Python 3.14) / Test (ubuntu-latest, Python 3.14)	35s
Publish RTC release	0s
docs	-1s
	15m 32s

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