Tag to be used with the main branch of atlas/athena. Update(s) since 2.0.168: - Updated GDB to version 13.2, while accounting for dependency changes in resolveAtlasAddr2Line; - Updated Acts to version v28.2.0; - Removed many outdated AtlasLCG modules; - Made Findsetuptools.cmake more robust for finding the module in different LCG versions; - Made AtlasCMake and AtlasLCG use C++20 with GCC 13+ by default; - Improved/fixed the C++20 build support in Boost, Eigen and Geant4; - Made CheckerGccPlugins ignore standard violations in code generated by GoogleTest, and switched it to using egrep instead of grep; - Introduced x86_64-el9-gcc13 builds in the CI.