Update Cargo.toml

Author: soutaro

rust/Cargo.lock

@@ -16,6 +16,7 @@ include = [
 
 [dependencies]
 ruby-rbs-sys = { version = "0.3", path = "../ruby-rbs-sys" }
+xxhash-rust = { version = "0.8", features = ["xxh3"] }
 
 [build-dependencies]
 serde = { version = "1.0", features = ["derive"] }