Bump `rand_core` to v0.10.0-rc-5 #2951

Job	Run time
build (stable, wasm32-unknown-unknown)	17s
build (1.85.0, thumbv7em-none-eabi)	21s
build (1.85.0, wasm32-unknown-unknown)	23s
build (stable, thumbv7em-none-eabi)	11s
test (stable)	18s
test (1.85.0)	25s
minimal-versions	0s
	1m 55s

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