As you can read at Office Dev Blog, Microsoft has just released a new edition of the Client Side Object Model (CSOM) for SharePoint Online (SPO). You can read the full announcement here: https://dev.office.com/blogs/new-sharepoint-csom-version-released-for-Office-365-may-2018
As always, this new CSOM version (16.1.7723.1200) is available via NuGet