Respect #[serde(transparent)] attribute (#17)

schemars_derive/src/attr/schemars_to_serde.rs

@@ -19,6 +19,7 @@ static SERDE_KEYWORDS: &[&str] = &[
     "skip_deserializing",
     "flatten",
     "remote",
+    "transparent",
     // Special cases - `with`/`serialize_with` are passed to serde but not copied from schemars attrs to serde attrs.
     // This is because we want to preserve any serde attribute's `serialize_with` value to determine whether the field's
     // default value should be serialized. We also check the `with` value on schemars/serde attrs e.g. to support deriving