Bump bdk_wallet version to 1.0.0-beta.6 #1410

Job	Run time
Build and test (stable, true, --no-default-features --features miniscript/no-std)	1m 25s
Build & Test Examples (example_cli)	9s
Build and test (stable, true, --all-features)	3m 56s
Build & Test Examples (example_bitcoind_rpc_polling)	29s
Build and test (1.63.0, --no-default-features --features miniscript/no-std)	2m 26s
Build & Test Examples (example_electrum)	41s
Check no_std	11s
Build and test (1.63.0, --all-features)	5m 4s
Build & Test Examples (example_esplora)	52s
Build & Test Examples (example_wallet_electrum)	45s
Check WASM	27s
Build & Test Examples (example_wallet_esplora_async)	52s
Rust fmt	6s
Build & Test Examples (example_wallet_esplora_blocking)	52s
Build & Test Examples (example_wallet_rpc)	30s
prepare	2s
clippy_check	29s
	19m 16s

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