Replace CMake command exec_program with execute_process

exec_program has been deprecated for quite some time and recent versions of CMake warn not to use it. See https://cmake.org/cmake/help/latest/policy/CMP0153.html

added Build modernisation labels

added RTA label

marked this merge request as draft

added lhcb-gaudi-head label

• [2024-02-06 17:08] Validation started with lhcb-gaudi-head#3814
• [2024-02-07 00:04] Validation started with lhcb-gaudi-head#3815
• [2024-02-08 00:04] Validation started with lhcb-gaudi-head#3816
• [2024-02-09 00:04] Validation started with lhcb-gaudi-head#3817

marked this merge request as ready

@sponce this is good to go. No ci-test needed because I tested it in lhcb-gaudi-head and with a special custom build with the latest CMake.

approved this merge request

merged

mentioned in commit a62ea0c7