Swift

Made all TrackLink properties `nil`. will never fail to decode TrackL… #350

Job	Run time
build_spotify_api_server	2m 58s
build_watch_os_mac_catalyst (platform=watchOS Simulator,name=Apple Watch Series 8 (45mm),OS=10.0)	2m 4s
test_linux (swift:5.6)	1m 3s
build_watch_os_mac_catalyst (platform=macOS,variant=Mac Catalyst)	1m 51s
test_linux (swift:5.7)	5m 18s
test_linux (swift:5.8)	4m 34s
test_macOS	4m 52s
test_other_platforms (platform=iOS Simulator,name=iPhone 15,OS=17.0)	11m 37s
test_linux (swift:5.9)	5m 46s
test_other_platforms (platform=tvOS Simulator,name=Apple TV,OS=17.0)	12m 24s
test_linux (swift:5.10)	5m 7s
	57m 34s

Provide feedback