chore: add std feature to serde

Author: iosh

crates/rpc/rpc-primitives/Cargo.toml

@@ -14,6 +14,6 @@ license-file.workspace = true
 
 [dependencies]
 rustc-hex = { workspace = true }
-serde = { workspace = true }
+serde = { workspace = true, features = ["std"] }
 serde_json = { workspace = true }
 serde-utils = { workspace = true }