Update cmake_minimum_required

[lukasm91]

cmake_minimum_required is outdated because of https://github.com/lukasm91/gtbench/blob/master/CMakeLists.txt#L60

This was added in CMake 3.24: https://cmake.org/cmake/help/latest/module/FetchContent.html

The error with CMake 3.22 is absolutely useless:

CMake Error at /gtbench/_deps/gridtools-subbuild/gridtools-populate-prefix/tmp/gridtools-populate-gitupdate.cmake:25 (message):
  Failed to get the hash for HEAD: