Updates multibuild to include multi-build/multibuild#542, so that if cmake is already available, the multibuild get_modern_cmake function does not attempt to install it when build_openjpeg or build_libjpeg_turbo is called.

The cmake install attempt on macOS uses brew, so this removes lines from the macOS wheel build like https://github.com/python-pillow/Pillow/actions/runs/12268369479/job/34230079347#step:5:4042

wheels/multibuild/library_builders.sh: line 203: brew: command not found