Bump ring dependency to 0.16.19

[andrekorol]

Bumping ring to 0.16.19 would fix compilation issues on crates that depend on jsonwebtoken as seen on Compilation fails on aarch64-apple-darwin and Build fail on Apple Silicon.

[ephemer]

@andrekorol I'm new to rust and blocked by this issue. That said, I can see that rust is already trying to compile ring v0.16.20 without this change and it still errors out:

error[E0432]: unresolved import `super::sysrand_chunk`
   --> /Users/~~~/.cargo/registry/src/github.com-1ecc6299db9ec823/ring-0.16.20/src/rand.rs:306:16
    |
306 |     use super::sysrand_chunk::chunk;
    |                ^^^^^^^^^^^^^ could not find `sysrand_chunk` in `super`

edit: ok never mind. I am building from an M1 Mac, so I thought this was relevant, but I can see that the issue is that I'm building for a wasm target: briansmith/ring#1043 (FYI for others who run into this)

[andrekorol]

@ephemer I'm also building from an M1 Mac and my build that depends on this jsonwebtoken crate only fails before running cargo update. It should be noted that running cargo update solves the problem.