Bump `cipher` to v0.5.0-pre.7 #299

Job	Run time
minimal-versions	0s
build (1.71.0, thumbv7em-none-eabi)	19s
build (1.71.0, wasm32-unknown-unknown)	18s
test (1.72.0)	17s
build (stable, thumbv7em-none-eabi)	27s
test (stable)	14s
build (stable, wasm32-unknown-unknown)	18s
	1m 53s

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