While msgpack has default binary-unicode conversion, the feature is
somehow disabled in ryu. As the other parts of ryu requires binary_type
data where they directly appear on-wire, simply follow the policy.
Signed-off-by: IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>