fix: use correct rand package for thread_rng #3002

Job	Run time
check no-default-features	29s
check serde	26s
clippy	1m 8s
check std	17s
docs	1m 3s
fmt	7s
test stable --no-default-features	1m 18s
test no_std	19s
test stable	1m 13s
test stable --all-features	1m 27s
test beta --no-default-features	1m 26s
test beta	1m 8s
test beta --all-features	1m 35s
test nightly --no-default-features	1m 14s
test nightly	1m 18s
test nightly --all-features	1m 22s
	15m 50s

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