switch cmake policy 0167 from OLD to NEW

This replaces #1047 (closed).

Old policy uses FindBoost.cmake provided by CMake, which is deprecated.

New policy uses BoostConfig.cmake provided by Boost. It returns targets Boost::ProgramOptions etc instead of library paths.

We still have to find out how to convert targets to paths for use in the configure_file command in MakePythonWheel.cmake. Asked at https://discourse.cmake.org/t/after-update-from-findboost-to-boostconfig-policy-0167-how-to-convert-library-targets-to-paths/13431