(fix): use serde without std

Author: vlad9486

Cargo.toml

@@ -22,4 +22,4 @@ auto_impl = "1.0"
 primitive-types = { version = "0.13", default-features = false }
 rlp = { version = "0.6", default-features = false, features = ["derive"] }
 sha3 = { version = "0.10", default-features = false }
-serde = { version = "1.0", features = ["derive"] }
+serde = { version = "1.0", default-features = false, features = ["derive"] }