minibytes: slightly optimize Bytes serde deserialize

Summary:
According to https://docs.rs/serde/latest/serde/trait.Deserializer.html#tymethod.deserialize_byte_buf
it seems `deserialize_byte_buf` is a better choice than `deserialize_bytes`.

Reviewed By: muirdm

Differential Revision: D64833693

fbshipit-source-id: f3dd6c2ecc3192413f4910cd088a9193135f04fd

eden/scm/lib/minibytes/src/serde.rs

@@ -89,7 +89,7 @@ impl<'de> de::Visitor<'de> for BytesVisitor {
 
 impl<'de> Deserialize<'de> for Bytes {
     fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
-        deserializer.deserialize_bytes(BytesVisitor)
+        deserializer.deserialize_byte_buf(BytesVisitor)
     }
 }