Update the win32metadata project to the latest AgilitySDK release

Microsoft D3D team has released a new Preview AgilitySDK point release, 1.721.1-preview. You can find the latest AgilitySDK Nuget package here: [Microsoft.Direct3D.D3D12.1.721.1-preview](https://www.nuget.org/packages/Microsoft.Direct3D.D3D12/1.721.1-preview)
