Understand why setting CMP0094 to NEW results in a failure on APPLE

[traversaro]

With policy_max set to 3.16, the macos config fails with:

loading initial cache file /Users/runner/work/robotology-superbuild/robotology-superbuild/.ci/initial-cache.gh.cmake
-- The C compiler identification is Clang 15.0.7
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /Users/runner/miniconda3/envs/test/bin/x86_64-apple-darwin13.4.0-clang - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- The CXX compiler identification is Clang 15.0.7
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /Users/runner/miniconda3/envs/test/bin/x86_64-apple-darwin13.4.0-clang++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Error at /Users/runner/miniconda3/envs/test/share/cmake-3.26/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
  Could NOT find Python3 (missing: Python3_LIBRARIES Development
  Development.Embed) (found version "3.11.6")
Call Stack (most recent call first):
  /Users/runner/miniconda3/envs/test/share/cmake-3.26/Modules/FindPackageHandleStandardArgs.cmake:600 (_FPHSA_FAILURE_MESSAGE)
  /Users/runner/miniconda3/envs/test/share/cmake-3.26/Modules/FindPython/Support.cmake:3766 (find_package_handle_standard_args)
  /Users/runner/miniconda3/envs/test/share/cmake-3.26/Modules/FindPython3.cmake:551 (include)
  CMakeLists.txt:36 (find_package)


-- Configuring incomplete, errors occurred!

[traversaro]

See also https://github.com/robotology/robotology-superbuild/actions/runs/6684105486/job/18161018643?pr=1509 :

-- Check for working CXX compiler: /Users/runner/miniconda3/envs/test/bin/x86_64-apple-darwin13.4.0-clang++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Error at /Users/runner/miniconda3/envs/test/share/cmake-3.26/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
  Could NOT find Python3 (missing: Python3_LIBRARIES Development
  Development.Embed) (found version "3.11.6")
Call Stack (most recent call first):
  /Users/runner/miniconda3/envs/test/share/cmake-3.26/Modules/FindPackageHandleStandardArgs.cmake:600 (_FPHSA_FAILURE_MESSAGE)
  /Users/runner/miniconda3/envs/test/share/cmake-3.26/Modules/FindPython/Support.cmake:3766 (find_package_handle_standard_args)
  /Users/runner/miniconda3/envs/test/share/cmake-3.26/Modules/FindPython3.cmake:551 (include)
  CMakeLists.txt:41 (find_package)


-- Configuring incomplete, errors occurred!