This release backports into the release/v0.9.x line the feature that added the prehash_compare_key boolean parameter to the top-level ProofSpec. When set to true, this flag causes keys to be consistently compared lexicographically according to their hashes within nonexistence proof verification, using the same hash function as specified by the already-extant prehash_key field.

This is a backwards-compatible change, as it requires opt-in via setting the prehash_compare_key flag to true in the ProofSpec. All existing ProofSpecs will continue to behave identically.

Changelog: https://github.com/cosmos/ics23/blob/master/CHANGELOG.md#091