Pact Python FFI

`pact-python-ffi` provides low-level Python bindings for the underlying Pact FFI (Foreign Function Interface) library, which is written in Rust. It enables Python applications to directly interact with the core Pact logic for contract testing. While often an internal dependency of the higher-level `pact-python` library, it can be used independently for advanced FFI control. The current version is `0.4.28.2`, and it is part of the `pact-python` monorepo, following its active release cadence.