Drop support for Swift 5.8 from Linux workflows #120

Job	Run time
Test with Docker / Linux (5.9 - jammy)	28s
Test with Docker / Windows (5.9 - windows-2022)	10m 42s
Test with Docker / Linux (5.10 - jammy)	31s
Test without Docker / Windows (5.9 - windows-2022)	4m 30s
Test with Docker / Windows (6.0 - windows-2022)	11m 55s
Test with Docker / Linux (6.0 - jammy)	39s
Test without Docker / Windows (6.0 - windows-2022)	4m 50s
Test with Docker / Windows (nightly - windows-2019)	8m 55s
Test with Docker / Linux (nightly-main - jammy)	36s
Test without Docker / Windows (nightly - windows-2022)	5m 1s
Test with Docker / Windows (nightly-6.1 - windows-2019)	9m 30s
Test with Docker / Linux (nightly-6.1 - jammy)	38s
Test without Docker / Windows (nightly-6.1 - windows-2022)	4m 49s
Test without Docker / Linux (${{ matrix.swift_version }} - ${{ matrix.os_version }})	0s
Soundness / API breakage check	0s
Soundness / Broken symlinks check	4s
Soundness / Documentation check	42s
Soundness / Format check	0s
Soundness / License headers check	5s
Soundness / Python lint check	9s
Soundness / Shell check	40s
Soundness / Unacceptable language check	2s
Soundness / YAML lint check	5s
	1h 4m 51s

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