Add missing imports to fix Swift 6.1+ #251

Job	Run time
Compatibility test	4m 56s
Unit tests / Construct unit test matrix	3s
Integration test / Windows (6.0)	3s
Integration test / Linux (5.9)	1m 47s
Integration test / Windows (nightly-6.0)	1s
Integration test / Linux (5.10)	1m 43s
Integration test / Windows (nightly-main)	2s
Integration test / Linux (6.0)	2m 1s
Integration test / Linux (nightly-6.0)	2m 13s
Integration test / Linux (nightly-main)	30s
Example packages / Linux (5.9)	18m 10s
Example packages / Windows (6.0)	1s
Example packages / Linux (5.10)	15m 41s
Example packages / Linux (6.0)	18m 44s
Example packages / Windows (nightly-6.0)	2s
Example packages / Windows (nightly-main)	3s
Soundness / API breakage check	0s
Soundness / Documentation check	1m 44s
Example packages / Linux (nightly-6.0)	22m 54s
Soundness / Unacceptable language check	8s
Example packages / Linux (nightly-main)	33s
Soundness / Broken symlinks check	3s
Soundness / Format check	34s
Soundness / License headers check	4s
Soundness / YAML lint check	0s
Soundness / Python lint check	7s
Soundness / Shell check	29s
Unit tests / Unit tests / Linux (5.9)	1m 34s
Unit tests / Unit tests / Linux (5.10)	1m 29s
Unit tests / Unit tests / Linux (6.0)	1m 47s
Unit tests / Unit tests / Linux (nightly-6.0)	2m 7s
Unit tests / Unit tests / Linux (nightly-main)	2m 57s
	1h 42m 30s

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