chore(msrv): bump MSRV to `1.85.0` #7638

Job	Run time
Rust fmt	17s
prepare	4s
Check no_std	17s
Check WASM	2m 9s
Build & Test (1.88.0, true, --no-default-features --features miniscript/no-std,bdk_chain/hashbrown)	59s
Build & Test (1.88.0, true, --all-features)	2m 53s
Build & Test (1.85.0, --all-features)	3m 8s
Build & Test (1.85.0, --no-default-features --features miniscript/no-std,bdk_chain/hashbrown)	55s
Rust clippy	28s
Build & Test Examples (example_cli)	22s
Build & Test Examples (example_electrum)	46s
Build & Test Examples (example_esplora)	53s
Build & Test Examples (example_bitcoind_rpc_polling)	33s
	13m 44s

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