Microsoft has released its weekly preview build of the Windows 10 SDK and, as usual, it matches the build number of the Windows 10 build that was made available to Insiders in the Fast ring last week. Microsoft hasn't published a blog post yet for this release, so it's not clear if there are any noteworthy changes, but if the current trend is kept up, there's probably not much in this release.
Regardless, the usual notes apply - you'll need to be running Insider builds of Windows 10 in order to use the SDK and you'll also need Visual Studio 2017 or newer. You can, however, use it alongside a stable release of the SDK, and continue publishing apps that target Windows 10 version 1903 or earlier.
If you're interested, you can download the latest SDK build from the Windows Insider website. You can also get the corresponding builds of the Assessment and Deployment Kit (ADK), Windows Driver Kit (WDK), and Hardware Lab Kit (HLK). There's usually a new build for Windows Server Insiders on Tuesdays as well but that doesn't seem to be the case today.
Update: Microsoft has published a blog post for this release, and it looks like this build actually includes some changes. First, there's a new NuGet feed for SDK builds, which lets you use tools such as the recently released WinRT API Pack. Microsoft has also removed WUAPICommon.H and WUAPICommon.IDL, with respective funtionality being moved to wuapi.h and wuapi.idl.