Nauty bindings: disable libc dependency

We don't need this as we don't use sparse graphs.

Cargo.toml

@@ -4,7 +4,7 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
-nauty-Traces-sys = "0.8.0"
+nauty-Traces-sys = { version = "0.8.0", default-features = false, features = ["bundled", "tls"] }
 union-find = "0.4.3"
 
 [profile.release-debug]