The `ThirtyTwoByteHash` trait is defined in `secp256k1` and used in
`hashes` as well as `bitcoin`. This means that we must use the same
version of `hashes` in both `bitcoin` and `secp256k1`. This makes doing
release difficult.
Remove usage of `ThirtyTwoByteHash` and use `Message::from_slice`.
Include TODO above each usage because as soon as we release the new
version of secp we can use the new `Message::from_digest`.
This is step backwards as far as type safety goes and it makes the code
more ugly as well because it uses `expect` but thems the breaks.
d9533523ac