ci: run Windows jobs on Namespace runners #828

Job	Run time
Test install.sh (Linux ARM64 glibc via QEMU)	2m 0s
Test vp-setup.exe (pwsh)	3m 3s
Test install.sh (readonly shell config)	11s
Test install.ps1 (Windows x64, PowerShell 7.6)	16s
Test install.sh (macOS x64)	40s
Test install.ps1 (Windows x64)	22s
Test install.sh (Linux x64 glibc)	15s
Test install.sh (macOS ARM64)	30s
Test install.ps1 (Windows x64, PowerShell 5.1)	23s
Test install.sh (Linux x64 musl)	20s
Test install.ps1 (minimum-release-age)	10s
Test install.ps1 (Windows ARM64)	54s
Test install.sh (Linux ARM64 musl via QEMU)	1m 21s
	10m 25s

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