The Vulkan API XML exposed as byte-string constant VKXML. Version is equal to the Vulkan version exposed - i.e. vkapi 1.0.0 exposes the vulkan 1.0.0 xml, vk_api 1.0.6 exposes the vulkan 1.0.6 xml, etc.
toml [build-dependencies] vk_api = "=1.0.9"