Release v0.23.0.

[hugopl]

Added

• Add support for Gio async functions (Add support for Gio async functions. #157).

Changed

• Requires Crystal compiler >= 1.6.0 (No PR 😁 2ebec2b).
• CI now uses newer libraries through Ubuntu 24.04 (Update CI to Ubuntu 24.04. #154).

Fixed

• Some code cleanup (Reviewing the generator code just to remember it's a mess. #155 Update CI checkout action to avoid node related warning. #156).