Add swift version file to record the Swift toolchain to use #181

Job	Run time
cmake-smoke-test / macOS (Xcode ${{ matrix.xcode_version }} - ${{ matrix.os_version }} - ${{ matrix.arch }})	0s
Test / macOS (Xcode ${{ matrix.xcode_version }} - ${{ matrix.os_version }} - ${{ matrix.arch }})	0s
Test / Linux (nightly-main - noble)	11m 41s
Test / Windows (nightly-main - windows-2019)	28m 5s
Test / Linux (nightly-main - jammy)	11m 46s
cmake-smoke-test / Linux (nightly-main - noble)	5m 26s
Test / Linux (nightly-main - focal)	12m 2s
Test / Linux (nightly-main - rhel-ubi9)	12m 0s
Test / Linux (nightly-6.2 - noble)	11m 48s
Test / Linux (nightly-6.2 - jammy)	12m 7s
Test / Linux (nightly-6.2 - focal)	12m 26s
Test / Linux (nightly-6.2 - rhel-ubi9)	12m 0s
Soundness / Broken symlinks check	4s
Soundness / API breakage check	0s
Soundness / Documentation check	1m 37s
Soundness / Format check	0s
Soundness / License headers check	14s
Soundness / Shell check	34s
Soundness / Unacceptable language check	3s
Soundness / Python lint check	9s
Soundness / YAML lint check	5s
	2h 12m 7s

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