bug(ci): macOS dependency build not using llvm 16

[sitaowang1998]

Bug

GitHub workflow build-macos is wrongly using AppleClang instead of llvm@16 to build dependencies. On macos-15 AppleClang is new enough to support C++20, but on macos-13 and macos-14 the version is too old.

In the workflow https://github.com/y-scope/clp/actions/runs/15975130844, the task deps:core log line 527-552 shows that the cmake is using AppleClang to build dependency.

-- The C compiler identification is AppleClang 15.0.0.15000100
-- The CXX compiler identification is AppleClang 15.0.0.15000100
-- The CXX compiler identification is AppleClang 15.0.0.15000100
-- The CXX compiler identification is AppleClang 15.0.0.15000100
-- The CXX compiler identification is AppleClang 15.0.0.15000100
-- The C compiler identification is AppleClang 15.0.0.15000100
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info
-- The CXX compiler identification is AppleClang 15.0.0.15000100
-- The CXX compiler identification is AppleClang 15.0.0.15000100
-- Detecting CXX compiler ABI info
-- The CXX compiler identification is AppleClang 15.0.0.15000100
-- The CXX compiler identification is AppleClang 15.0.0.15000100
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info
-- The CXX compiler identification is AppleClang 15.0.0.15000100
-- Detecting CXX compiler ABI info
-- The C compiler identification is AppleClang 15.0.0.15000100
-- Detecting CXX compiler ABI info
-- The CXX compiler identification is AppleClang 15.0.0.15000100
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /Applications/Xcode_15.2.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ - skipped
-- Detecting CXX compile features

Unlike the dependencies, CLP itself is correctly built with llvm@16 because we manually sets the compilers in CMake.

CLP version

f1d379d

Environment

macOS

Reproduction steps

Run the GitHub workflow.