Support Xcode 16

[liamnichols]

Adds Xcode 16 to the CI test matrix, therefore guaranteeing support with Swift 6/Xcode 16 developer environment.

[github-actions]

✅ Pull Request passed benchmark checks

Summary

Wed Jun 19 11:42:16 UTC 2024

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Threshold deviations for StringGenerator.generateSource(for:tableName:accessLevel:):XCStringsToolBenchmarks
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Time (total CPU) (ms, %)	main	pull_request	Difference %	Threshold %
p25	1565	1848	18	5
p50	1565	1848	18	5
p75	1565	1848	18	5

New baseline 'pull_request' is WORSE than the 'main' baseline thresholds.

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Comparing results between 'main' and 'pull_request'

Host 'Mac-1718795691324.local' with 3 'arm64' processors with 7 GB memory, running:
Darwin Kernel Version 23.5.0: Wed May  1 20:12:39 PDT 2024; root:xnu-10063.121.3~5/RELEASE_ARM64_VMAPPLE

XCStringsToolBenchmarks

StringGenerator.generateSource(for:tableName:accessLevel:) metrics

Time (total CPU) (ms) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	1565	1565	1565	1565	1565	1565	1565	1
pull_request	1848	1848	1848	1848	1848	1848	1848	1
Δ	283	283	283	283	283	283	283	0
Improvement %	-18	-18	-18	-18	-18	-18	-18	0