cpptoml dependency expects ancient CMake version

# Description

The [cpptoml package](https://github.com/chadaustin/cpptoml/) used by Watchman looks unmaintained, and starting with CMake 4 fails to configure as CMake dropped compatibility for older versions. Please either update it with a new fork or switch to a better-maintained TOML library.

Ref: https://bugs.gentoo.org/952105