bump zk back down to 3.4.x
bump zk back down to 3.4.x

HubSpot/Singularity,HubSpot/Singularity,hs-jenkins-bot/Singularity,hs-jenkins-bot/Singularity,hs-jenkins-bot/Singularity,HubSpot/Singularity,hs-jenkins-bot/Singularity,hs-jenkins-bot/Singularity,HubSpot/Singularity,HubSpot/Singularity