Remove Miri equality workaround function

[AaronFeickert]

When testing with Miri, hash equality is checked using a workaround function that attempts to mimic constant-time functionality. This was done only because the constant_time_eq crate was not compatible with Miri.

However, thanks to a PR by @oconnor663, this incompatibility is no longer present, which means the workaround can be safely removed. This PR does so.

[oconnor663]

LGTM, though it looks like it needs a tweak to pass CI:

error[E0277]: can't compare `[u8; 32]` with `&[u8; 32]`
   --> src/lib.rs:339:23
    |
339 |         return self.0 == other;
    |                       ^^ no implementation for `[u8; 32] == &[u8; 32]`
    |
    = help: the trait `std::cmp::PartialEq<&[u8; 32]>` is not implemented for `[u8; 32]`
help: consider dereferencing here
    |
339 |         return self.0 == *other;
    |                          +

[AaronFeickert]

Good catch! I'm surprised that my IDE didn't complain about this. Will update.

[AaronFeickert]

Should be good to go now.

[AaronFeickert]

@oconnor663: This is now updated to account for the new constant_time_eq version that includes your fix.

[oconnor663]

Thanks!