chore: remove some outdated apps

[Kazhnuz]

• Cawbird : Abandonned
• Pdftag : No release since 5 years ago on github, no activity since two years ago
• Games : Looks like Highscore isn't ready for now, and will be replaced by Alice's highscore2 project. I feel that removing Games for now is better
• Dynamic Wallpaper Editor - Utility for editing GNOME's XML wallpapers
• Passbook : Unmaintained since a year

( There are certainly more to clean, I'll go back to this PR in a few days )