build: macOS: bump clang from 14.0.0

Just a tracking issue. There's no extreme pressure to upgrade.

`macos-12` currently uses clang ~13.1.6~ 14.0.0 by default.

Edit: It was unexpected to me that it was silently updated in https://github.com/actions/runner-images/commit/9dcc6a79fa98209c2f605500b107b2f672ca12fc.

Links:

- https://github.com/actions/runner-images/blob/main/images/macos/macos-12-Readme.md
- https://github.com/exercism/configlet/commit/88046f4682643a1cbac2b1d3b3d62ebf123a2ac2 github(workflows): bump macOS from 11 to 12
- https://releases.llvm.org
- https://github.com/llvm/llvm-project/releases

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Tracking issues for C compilers on the other platforms:
- https://github.com/exercism/configlet/issues/658
- https://github.com/exercism/configlet/issues/570