Add beamspot sigmaZ to output
We should add sigmaZ to the output as this would be nice for finalfits: https://cms-nanoaod-integration.web.cern.ch/autoDoc/NanoAODv12/2022/2023/doc_DYJetsToLL_M-50_TuneCP5_13p6TeV-madgraphMLM-pythia8_Run3Summer22NanoAODv12-130X_mcRun3_2022_realistic_v5-v2.html#BeamSpot