[directml] Update to 1.15.2

[luncliff]

Changes

Update to the latest NuGet release

References

• https://www.nuget.org/packages/Microsoft.AI.DirectML/1.15.2
• https://github.com/microsoft/DirectML/blob/master/Releases.md

Triplet Support

• Windows triplets
• x64-linux

Configuration

"vcpkg-configuration.json" changes for the release.

{
    "registries": [
        {
            "kind": "git",
            "repository": "https://github.com/luncliff/vcpkg-registry",
            "packages": [
                "directml"
            ],
            "baseline": "..."
        }
    ]
}