Add cumprod (#1491) #436

Job	Run time
Pass MSRV values to other jobs	3s
format/nightly	13s
clippy/stable	22s
nostd/thumbv6m-none-eabi/stable	17s
miri	8m 39s
cross_test/s390x-unknown-linux-gnu/stable	7m 21s
docs/nightly	21s
cross_test/i686-unknown-linux-gnu/stable	1m 38s
cargo-careful	2m 15s
blas-msrv	39s
tests/beta	2m 43s
tests/nightly	3m 18s
tests/1.64.0	3m 34s
tests/stable	2m 27s
conclusion	3s
	33m 53s

Provide feedback