Update default CMake version and GCC to benefits new features
Description
According to #1451 (closed) change python import module going from CMake default 3.9 to CMake 3.12.
Update Gcc version to v15 to benefits new features.
Code version and environment identification
Analysis
See https://cmake.org/cmake/help/latest/module/FindPython3.html for new features
Security impact
N.A