Missing VK_KHR_portability_subset device extension

[ChristianIvicevic]

I am currently learning Rust and Vulkan and following the tutorial with your repository. Since I am on macOS and using MoltenVK I got a validation error enforcing VK_KHR_portability_subset when the device supports it. After some trial and error I was finally able to fix the validation error: https://github.com/ChristianIvicevic/blight/commit/a32f3a40d14829e76aab71fe8dbb565588fbf4e2

Are you open for a PR to add this check to your repository as well?

[adrien-ben]

Hi, sorry for the late response. Yes I open to PRs :)