bump `digest`/`cipher` to `0.11.0-pre.8`/`0.5.0-pre.4` #293

Job	Run time
build (1.72.0, thumbv7em-none-eabi)	15s
test (1.72.0)	27s
build (1.72.0, wasm32-unknown-unknown)	16s
test (stable)	20s
build (stable, thumbv7em-none-eabi)	19s
build (stable, wasm32-unknown-unknown)	8s
minimal-versions / minimal-versions	44s
	2m 29s

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