Companion for paritytech/substrate#12828 (#1939)

* Companion for paritytech/substrate#12764

* Remove `async-trait`

* Companion for paritytech/substrate#12828

* carg fmt

* Update client/relay-chain-minimal-node/src/network.rs

Co-authored-by: Bastian Köcher <git@kchr.de>

* update lockfile for {"polkadot", "substrate"}

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Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: parity-processbot <>