bcrypt-pbkdf: scrypt: bump cipher to `0.5.0-pre.4` #873

Job	Run time
build (1.72.0, thumbv7em-none-eabi)	17s
test (1.72.0)	28s
build (1.72.0, wasm32-unknown-unknown)	24s
test (stable)	14s
build (stable, thumbv7em-none-eabi)	21s
build (stable, wasm32-unknown-unknown)	26s
minimal-versions / minimal-versions	12s
	2m 22s

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