Added C++23 as a standard option

[veygax]

github copilot summary since the change is basic:

This pull request updates the cpp_lang definition in the cmake-init/cmake_init.py file to include support for the C++23 standard.

• Language Support Update:
  • cmake-init/cmake_init.py: Added "23" to the list of supported standards for the cpp_lang object, enabling compatibility with C++23.

[friendlyanon]

C++23 support by cmake-init is on hold until modules and import std; are properly supported by compilers and GitHub CI's images provide such working toolchains by default.