Use slc6 when running athena in CI
Need to do (instructions from Frank)
setupATLAS -c slc6
singularity exec -e --no-home -B /cvmfs /cvmfs/atlas.cern.ch/repo/containers/fs/singularity/x86_64-centos6 /bin/bash -- run_athena.shNeed to do (instructions from Frank)
setupATLAS -c slc6
singularity exec -e --no-home -B /cvmfs /cvmfs/atlas.cern.ch/repo/containers/fs/singularity/x86_64-centos6 /bin/bash -- run_athena.sh