[sdl3-shadercross] Update to 3.0.0-preview2

[lammmab]

• Changes comply with the maintainer guide.
• SHA512s are updated for each updated download.
• The "supports" clause reflects platforms that may be fixed by this new version, or no changes were necessary.
• Any fixed CI baseline and CI feature baseline entries are removed from that file, or no entries needed to be changed.
• All patch files in the port are applied and succeed.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Exactly one version is added in each modified versions file.

[lammmab]

@microsoft-github-policy-service agree

[lammmab]

x86-windows target builds successfully on a local machine using a fresh vcpkg clone on Windows 10. CI failure appears to be environment-specific.

[Pucas01]

Would love to see this get merged

[BillyONeal]

Thanks!