During the last round of releases (bitcoin 0.30, hashes 0.12) we removed
the `FromHex` implementation from all types except vecs and arrays. We
added `FromStr` impls for types that roundtrip with `Display`.
We never added a changelog mention to either `bitcoin` or `hashes`, lets
retroactively add an entry.
Fix: #1747
Recently we added a workspace but left the CHANGELOG file at the
repository root, this is incorrect because the CHANGELOG is a per crate
thing since it is updated along with crate release.