swift-cmark 0.9.0

This release is based on the current state of release/6.4.x, which includes a change cherry-picked for (as-yet unreleased) Swift 6.4.3.

What's Changed

• 🍒 6.4: Replace UTF-8 chars with hex escape sequence by @speednoisemovement in #98

Full Changelog: 0.8.0...0.9.0