27th of April was the release date of new LTS (Long Term Support) version of Ubuntu Linux distribution - Ubuntu 18.04 Bionic Beaver. Although, there is no 18.04 image in Azure Marketplace yet.
But official, stable image (not DAILY) is already there. To find it and use it, you need to use Azure CLI (or PowerShell).
To find it, use:
az vm image list --all -p Canonical -f UbuntuServer -s 18.04-LTS --query .urn -o tsv
Find the one with "18.04-LTS" SKU.
Then, to deploy it, use:
az vm create -n MyVm -g MyResourceGroup --image Canonical:UbuntuServer:18.04-LTS:18.04.201804262