centos7, HepMC3, LCG_104d_ATLAS_13 contains MRs: https://gitlab.cern.ch/atlas/athena/-/merge_requests/70521 add new ART tests for Generators https://gitlab.cern.ch/atlas/athena/-/merge_requests/70473 LCG_104d_ATLAS_13: switch to a new lcg layer https://gitlab.cern.ch/atlas/athena/-/merge_requests/70681 Disable further default arguments in HepMcParticleLink constructors https://gitlab.cern.ch/atlas/athena/-/merge_requests/70697 GENtoEVGEN: Do not crash if no release is defined https://gitlab.cern.ch/atlas/athena/-/merge_requests/70690 Add Exec.FirstEvent flag and configure McEventSelector for 64-bit events