rococo: some initial thing

polkadot/runtime/rococo/Cargo.toml

@@ -104,6 +104,7 @@ polkadot-parachain-primitives = { path = "../../parachain", default-features = f
 xcm = { package = "staging-xcm", path = "../../xcm", default-features = false }
 xcm-executor = { package = "staging-xcm-executor", path = "../../xcm/xcm-executor", default-features = false }
 xcm-builder = { package = "staging-xcm-builder", path = "../../xcm/xcm-builder", default-features = false }
+serde_json = { version = "1.0.108", default-features = false, features = ["alloc"] }
 
 [dev-dependencies]
 tiny-keccak = { version = "2.0.2", features = ["keccak"] }
@@ -111,7 +112,6 @@ keyring = { package = "sp-keyring", path = "../../../substrate/primitives/keyrin
 remote-externalities = { package = "frame-remote-externalities", path = "../../../substrate/utils/frame/remote-externalities" }
 sp-trie = { path = "../../../substrate/primitives/trie" }
 separator = "0.4.1"
-serde_json = "1.0.108"
 sp-tracing = { path = "../../../substrate/primitives/tracing", default-features = false }
 tokio = { version = "1.24.2", features = ["macros"] }
 
@@ -191,6 +191,7 @@ std = [
 	"scale-info/std",
 	"serde/std",
 	"serde_derive",
+	"serde_json/std",
 	"sp-api/std",
 	"sp-arithmetic/std",
 	"sp-core/std",