Update to simd-json 0.12

Author: dtolnay

Cargo.toml

@@ -11,7 +11,7 @@ jemallocator = "0.5"
 rustc-serialize = { version = "0.3", optional = true }
 serde = { version = "1.0", features = ["derive"], optional = true }
 serde_json = { version = "1.0", optional = true }
-simd-json = { version = "0.11", optional = true }
+simd-json = { version = "0.12", optional = true }
 
 [features]
 default = ["performance", "all-libs", "all-files"]