Merge bitcoindevkit/bdk#1613: ci: automated update to rustc 1.81.0 #6094

Job	Run time
Check WASM	58s
Build and test (stable, true, --no-default-features)	3m 38s
prepare	3s
Build and test (stable, true, --all-features)	3m 43s
Build Examples (example_cli)	26s
Build and test (1.63.0, --no-default-features)	4m 52s
Build Examples (example_bitcoind_rpc_polling)	31s
Check no_std	30s
Build and test (1.63.0, --all-features)	5m 0s
Build Examples (example_electrum)	46s
Build Examples (example_esplora)	47s
Build Examples (wallet_electrum)	44s
Rust fmt	7s
Build Examples (wallet_esplora_async)	48s
Build Examples (wallet_esplora_blocking)	1m 2s
Build Examples (wallet_rpc)	32s
clippy_check	3m 46s
	28m 13s

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