SPI-2626: LCG_106_ATLAS_7_8
The layer request is described in SPI-2626. It is based on top of LCG_106_ATLAS_5/6 and it has the following changes wrt:
- Pythia8 is updated to 312, contains a patch described in SPI-2625 and released as pythia8-312.atlas1
- Sherpa has been updated to a patched version of Sherpa-3.0.0, which incorporates the patch from https://gitlab.com/sherpa-team/sherpa/-/merge_requests/917/diffs and releases as Sherpa-3.0.0p1
- The Sherpa build option -DSHERPA_ENABLE_EWSUD is now enabled (ON)