VKD3D-Proton 3.1 stable release adds Shader Model 6.9 support

VKD3D-Proton 3.1, the Direct3D 12 translation layer used in Valve's Proton, is out as a stable release. It adds Shader Model 6.9, KHR_opacity_micromap, DXR 1.2 and ray-tracing optimizations, while VK_EXT_descriptor_heap stays opt-in due to driver quality concerns.

• Shader Model 6.9 support added, currently only active on NVIDIA GPUs
• VK_EXT_descriptor_heap not enabled by default over driver quality concerns
• Steam Frame is now a supported platform with aarch64 builds
• COPY and RTAS barrier optimizations boost ray-tracing performance