feat: update unsigned-varint to v0.5

Signed-off-by: koushiro <koushiro.cqx@gmail.com>

Author: koushiro

Cargo.toml

@@ -18,7 +18,7 @@ digest = { version = "0.9", default-features = false }
 sha-1 = { version = "0.9", default-features = false }
 sha2 = { version = "0.9", default-features = false }
 sha3 = { version = "0.9", default-features = false }
-unsigned-varint = "0.4"
+unsigned-varint = "0.5"
 quickcheck = { version = "0.9.2", optional = true }
 rand = { version = "0.7.3", optional = true }