Update the zeroize depdency.

[Superhepper]

We should move to a newer version of the Zeroize crate and start using ZeroizeOnDrop in stead of

#[derive(zeroize)]
#[zeroize(drop)]

because it will be deprecated in newer releases.

It would also be a good time to have a look at if all native types that should be using zeroize on drop actually are. And make sure that we allocate the full capacity of the buffers we use to avoid re-allocation of the data which could leave copy of the data in memory.

Read Stack/Heap Zeroing Notes

[Superhepper]

Partially fixed by #378 .