Bump `rand_core` to v0.10; `getrandom` to v0.4 (#2198) #2511

Job	Run time
test (stable)	1m 8s
build (stable, thumbv7em-none-eabi)	27s
build (1.85.0, wasm32-unknown-unknown)	28s
build (stable, wasm32-unknown-unknown)	18s
build (1.85.0, thumbv7em-none-eabi)	28s
test (1.85.0)	1m 19s
minimal-versions	0s
	4m 8s

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