Update Substrate/Polkadot/Cumulus references
cumulus: b468d0c33eac0adda27080b59ea9b5986ce6469b
polkadot: 827792ca833396c82c726eda0bc2ad32ecddba73
substrate: 666f39b8a22108f57732215de006518738034ba2
bump serde_json to 1.0.79
sync changes from https://github.com/paritytech/substrate/pull/11022
fixed clippy warnings
Signed-off-by: acatangiu <[email protected]>