fix(updatenotification): harden git command execution + simplify checkUpdates#4115

khassel merged 2 commits intoMagicMirrorOrg:developMagicMirrorOrg/MagicMirror:developfrom

KristjanESPERANTO:fix/updatenotificationKristjanESPERANTO/MagicMirror:fix/updatenotificationCopy head branch name to clipboard