enable union feature of smallvec

Author: mockersf

wgpu-hal/Cargo.toml

@@ -51,7 +51,7 @@ foreign-types = { version = "0.3", optional = true }
 ash = { version = "0.37", optional = true }
 gpu-alloc = { version = "0.5", optional = true }
 gpu-descriptor = { version = "0.2", optional = true }
-smallvec = { version = "1", optional = true }
+smallvec = { version = "1", optional = true, features = ["union"] }
 
 # backend: Gles
 glow = { version = "0.11.1", optional = true }