bcrypt-pbkdf: scrypt: bump cipher to `0.5.0-pre.4` #886

Job	Run time
build (1.72.0, thumbv7em-none-eabi)	21s
build (1.72.0, wasm32-unknown-unknown)	22s
minimal-versions	0s
test (1.72.0)	20s
build (stable, thumbv7em-none-eabi)	1m 3s
test (stable)	21s
build (stable, wasm32-unknown-unknown)	1m 47s
	4m 14s

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