Drop Swift 5.9 #60

Job	Run time
Cxx interop / Construct Cxx interop matrix	3s
macOS tests / Construct Darwin matrix	4s
Unit tests / Construct unit test matrix	3s
Soundness / API breakage check	47s
Soundness / Broken symlinks check	2s
Soundness / Documentation check	57s
Soundness / Format check	32s
Soundness / License headers check	3s
Soundness / Python lint check	5s
Soundness / Shell check	31s
Soundness / Unacceptable language check	3s
Soundness / YAML lint check	3s
Static SDK / Static SDK / Linux (latest-release Jammy)	1m 29s
Static SDK / Static SDK / Linux (main Jammy)	1m 44s
Cxx interop / Cxx interop / Linux (5.9)	31s
Cxx interop / Cxx interop / Linux (5.10)	41s
Cxx interop / Cxx interop / Linux (6.0)	44s
Cxx interop / Cxx interop / Linux (6.1)	50s
Cxx interop / Cxx interop / Linux (nightly-next)	56s
Cxx interop / Cxx interop / Linux (nightly-main)	53s
Unit tests / Unit tests / Linux (5.9)	27s
Unit tests / Unit tests / Linux (5.10)	36s
Unit tests / Unit tests / Linux (6.0)	44s
Unit tests / Unit tests / Linux (6.1)	42s
Unit tests / Unit tests / Linux (nightly-next)	50s
Unit tests / Unit tests / Linux (nightly-main)	1m 1s
macOS tests / Xcode 16.1	1m 15s
macOS tests / Xcode 16.2	1m 13s
macOS tests / Xcode 16.3	1m 18s
	19m 7s

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