Update toolchain to nightly-2025-05-09 (1.88) #73

Job	Run time
build_with_vcpkg_installed_z3 (linux)	32m 31s
build_with_vcpkg_installed_z3 (macos)	26m 13s
build_with_vcpkg_installed_z3 (windows)	54m 12s
	1h 52m 56s

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