bump `digest`/`cipher` to `0.11.0-pre.8`/`0.5.0-pre.4` #46

Job	Run time
build (1.71.0, thumbv7em-none-eabi)	16s
minimal-versions	0s
build (1.71.0, wasm32-unknown-unknown)	15s
test (1.71.0)	14s
build (stable, thumbv7em-none-eabi)	21s
test (stable)	9s
build (stable, wasm32-unknown-unknown)	8s
	1m 23s

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