release/21.6.95

Ewelina Maria Lobodzinska

@ewelina

bb359059 · Update version.txt · May 30, 2022

contains MRs:

 https://gitlab.cern.ch/atlas/athena/-/merge_requests/53473 Pythia8.306 , release 21.6.95  

https://gitlab.cern.ch/atlas/athena/-/merge_requests/53476 Generators: Rivet README update