Depend on futures-util instead of futures

Cargo.toml

@@ -28,7 +28,7 @@ unexpected_cfgs = { level = "warn", check-cfg = [
 ] }
 
 [dependencies]
-futures = { version = "0.3", default-features = false, features = ["std"] }
+futures-util = { version = "0.3", default-features = false, features = ["std"] }
 parking_lot = "0.12"
 dagx-macros = { version = "0.3.1", path = "./dagx-macros" }
 tracing = { version = "0.1", optional = true }