devel/g-golf: update to 0.8.0-a.5
Summary of changes:
- Templates
- Derived class improvements
- SXML support
- Emacs experimental addon sxml-ui.el (in examples/adw-1/adw1-demo/ui)
- Adwaita demo
- Bug fixes
Full changes: https://www.gnu.org/software/g-golf/news.html
PR: 273493