Summary:
This release accommodates rust-payjoin 0.21.0, using a payjoin v2-first
API and exposing bitcoin-ffi types directly.
Changelog:
- Major overhaul to attempt a stable BIP 77 protocol implementation.
- v1 support is now only available through the V2 backwards-compatible APIs.
- see [payjoin-0.21.0 changelog](https://github.com/payjoin/rust-payjoin/blob/master/payjoin/CHANGELOG.md#0210) for more details.
- Separate `payjoin_ffi` and `payjoin_ffi::uni` UniFFI types into two layers.
- Re-export bitcoin-ffi types and their UniFFI bindings
