Turn on Swift 6 mode in examples project. #710

Job	Run time
Library Evolution (16.2)	7m 57s
Wasm	2m 36s
library-15-4-compatibility (15.4, 17.5, ios)	5m 19s
library (16.2, ios)	6m 54s
Windows (windows-latest, debug)	5m 40s
library (16.2, macos)	3m 57s
Windows (windows-latest, release)	14m 25s
library (16.2, tvos)	5m 23s
library (16.2, watchos)	5m 13s
library (16.2, examples)	10m 26s
	1h 7m 50s

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