chore[chain,wallet]: fix build warnings #6495

Job	Run time
prepare	5s
Check no_std	20s
Build & Test Examples (example_cli)	22s
Build and test (stable, true, --no-default-features --features miniscript/no-std)	1m 29s
Build & Test Examples (example_bitcoind_rpc_polling)	28s
Check WASM	35s
Build and test (stable, true, --all-features)	3m 49s
Build & Test Examples (example_electrum)	50s
Build & Test Examples (example_esplora)	1m 1s
Rust fmt	44s
Build & Test Examples (example_wallet_electrum)	1m 2s
Build and test (1.63.0, --no-default-features --features miniscript/no-std)	2m 42s
Build & Test Examples (example_wallet_esplora_async)	1m 1s
Build & Test Examples (example_wallet_esplora_blocking)	55s
Build and test (1.63.0, --all-features)	5m 25s
Build & Test Examples (example_wallet_rpc)	47s
clippy_check	26s
	22m 1s

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