Enable generic-array's more_lengths feature (digest crate)

[wtfsck]

generic-array's feature more_lengths enables more Into<[T; $n]> implementations which are useful when converting the result to an array. Right now it's only possible to do this if the hash size is at most 32 bytes. With this feature it's possible to also do it up to size 64 and some select sizes > 64, see the code below.

https://github.com/fizyk20/generic-array/blob/d4d63b7ea425f42a7e373510f95eb36ed17d34c4/src/impls.rs#L218-L251

traits/digest/Cargo.toml

Line 15 in d3e5448

generic-array = "0.14.4"

[tarcieri]

You are free to enable it yourself if you wish. That's how cargo features work.

[newpavlov]

It may be worth to enable this feature in crypto-common. It could simplify some of our code and improve user ergonomics, while impact on compile time should be negligible (assuming that the linked impls is the only thing enabled by this feature).

[wtfsck]

You are free to enable it yourself if you wish. That's how cargo features work.

I'm not using generic-array directly, only indirectly through the sha2 crate. It depends on digest which does not enable the feature.

Adding generic-array to my own crate so this feature can be enabled in a dependency of a dependency works but is a hack, and it will probably stop working when digest bumps its generic-array dependency version to eg. 0.15 while my crate still uses 0.14 (latest at this time).