Rust crate updates

[str4d]

Closes #189.

[gmale]

Thanks, we literally just made a issue for this thinking we'd have to figure it out! :laughing:

We can probably close that now and merge this! :tada:

[pacu]

@str4d I'm having troubles to compile this on rustc 1.40.0, is the assertion issue fixed on with this pr as well? Could this error be tied to the compiler version ?

error[E0210]: type parameter `T` must be used as the type parameter for some local type (e.g., `MyStruct<T>`)
   --> /Users/pacu/.cargo/registry/src/github.com-1ecc6299db9ec823/subtle-2.3.0/src/lib.rs:510:6
    |
510 | impl<T> From<CtOption<T>> for Option<T> {
    |      ^ type parameter `T` must be used as the type parameter for some local type
    |
    = note: only traits defined in the current crate can be implemented for a type parameter

error: aborting due to previous error

For more information about this error, try `rustc --explain E0210`.
error: could not compile `subtle`.

[gmale]

try cargo clean and then cargo update, I suspect that might fix that issue.

[pacu]

@str4d I got it to build by upgrading the rust compiler to 1.46.0, but then I got into the assertion issue #177