Loupe no longer allows generative AI contributions

[alicem (Alice Mikhaylenko)]

Added it in:

• World / Elastic · GitLab
• CONTRIBUTING.md · main · GNOME / libadwaita · GitLab
• CONTRIBUTING.md · main · GNOME / libmanette · GitLab
• Alice Mikhaylenko / libhighscore · GitLab
• CONTRIBUTING.md · main · World / Highscore · GitLab

Thanks!