avoid KeyError when track is already unpublished #1621

Job	Run time
Make RTC sdist	13s
Build RTC wheels (AMD64)	1m 38s
Build RTC wheels (aarch64)	1m 18s
Generating protobuf	23s
Build RTC wheels (x86_64)	50s
Build RTC wheels (x86_64 arm64)	57s
Test (ubuntu-latest, Python 3.12) / Test (ubuntu-latest, Python 3.12)	1m 37s
Test (ubuntu-latest, Python 3.10) / Test (ubuntu-latest, Python 3.10)	1m 21s
Test (macos-latest, Python 3.12) / Test (macos-latest, Python 3.12)	2m 55s
Test (macos-latest, Python 3.14) / Test (macos-latest, Python 3.14)	2m 36s
Test (ubuntu-latest, Python 3.11) / Test (ubuntu-latest, Python 3.11)	1m 26s
Test (ubuntu-latest, Python 3.9) / Test (ubuntu-latest, Python 3.9)	1m 45s
Test (windows-latest, Python 3.14) / Test (windows-latest, Python 3.14)	1m 54s
Test (windows-latest, Python 3.9) / Test (windows-latest, Python 3.9)	2m 26s
Test (windows-latest, Python 3.12) / Test (windows-latest, Python 3.12)	2m 13s
Test (ubuntu-latest, Python 3.14) / Test (ubuntu-latest, Python 3.14)	1m 25s
Test (ubuntu-latest, Python 3.13) / Test (ubuntu-latest, Python 3.13)	1m 24s
Test (macos-latest, Python 3.9) / Test (macos-latest, Python 3.9)	2m 23s
Publish RTC release	0s
docs	0s
	28m 44s

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