contains MRs: https://gitlab.cern.ch/atlas/athena/-/merge_requests/42466 MCTC sync with 21.2 https://gitlab.cern.ch/atlas/athena/-/merge_requests/42515 update to Rivet 3.1.4/YODA 1.9.0 https://gitlab.cern.ch/atlas/athena/-/merge_requests/42541 add OLPATH as environment variable https://gitlab.cern.ch/atlas/athena/-/merge_requests/42549 update PowhegControl version to -05-00 https://gitlab.cern.ch/atlas/athena/-/merge_requests/42558 New Pythia8 Hooks for showering Powheg events https://gitlab.cern.ch/atlas/athena/-/merge_requests/42573 OpenLoops correct setup of env. variables https://gitlab.cern.ch/atlas/athena/-/merge_requests/42600 Sherpa_i README update https://gitlab.cern.ch/atlas/athena/-/merge_requests/42624 Update/expand decay channel selection for Powheg ttW