feat(bdk_electrum): add `use-openssl` as a feature #6139

Job	Run time
Check WASM	2m 45s
Check no_std	2m 31s
Build & Test Examples (example_cli)	2m 26s
Build and test (stable, true, --no-default-features --features miniscript/no-std)	3m 49s
Rust fmt	7s
Build & Test Examples (example_bitcoind_rpc_polling)	29s
Build and test (stable, true, --all-features)	3m 59s
prepare	5s
Build & Test Examples (example_electrum)	51s
Build and test (1.63.0, --no-default-features --features miniscript/no-std)	4m 25s
Build & Test Examples (example_esplora)	53s
Build and test (1.63.0, --all-features)	5m 20s
Build & Test Examples (example_wallet_electrum)	58s
Build & Test Examples (example_wallet_esplora_async)	1m 6s
Build & Test Examples (example_wallet_esplora_blocking)	51s
Build & Test Examples (example_wallet_rpc)	32s
clippy_check	2m 47s
	33m 54s

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