RUSTSEC-2020-0146: arr! macro erases lifetimes

[github-actions]

arr! macro erases lifetimes

Details
Package	generic-array
Version	0.12.3
URL	fizyk20/generic-array#98
Date	2020-04-09
Patched versions	>=0.14.0
Unaffected versions	<0.8.0

Affected versions of this crate allowed unsoundly extending
lifetimes using arr! macro. This may result in a variety of
memory corruption scenarios, most likely use-after-free.

See advisory page for additional details.

[tmpolaczyk]

While we do not use the arr! macro in this repository, some of our dependencies may have some issues because of this, so we should update those dependencies.

All of them are dependencies of witnet_crypto, so I tried running cargo upgrade -p witnet_crypto, but that didn't work because of dependency conflicts. So we probably need to update all of the dependencies to fix this issue.

[mbrubeck]

A patched version generic-array 0.12.4 is now available, so you can now fix this just by running:

cargo update -p generic-array:0.12.3