[FEAT] List of currently unsupported package managers

I'm making a list of package managers currently unsupported by fastfetch, currently I have:
- [AppImage](https://github.com/AppImage/AppImageKit/)
- [Devbox](https://www.jetify.com/devbox)
- [Rad](https://github.com/glaucuslinux/rad/tree/main)
- [ScratchPKG](https://gitlab.com/venomlinux/scratchpkg)
- [TCE](https://wiki.tinycorelinux.net/doku.php?id=wiki:package_management_cheat_sheet)
- [CPT](https://fossil.carbslinux.org/cpt/doc/trunk/www/index.md)
- [KISS](https://codeberg.org/kiss-community/kiss)
- [Pacstall](https://github.com/pacstall/pacstall)
- [NPM](https://github.com/npm/cli)
- [pip](https://github.com/pypa/pip)
- [Bonsai](https://github.com/mitchweaver/bonsai)
- [URPMI](https://wiki.mageia.org/en/URPMI)
- [Birb](https://github.com/birb-linux/birb/tree/dev)

(Let me know if I have missed any!)
Are these going to be supported in the future?

L’issue elenca gestori di pacchetti che fastfetch attualmente non supporta, ma non indica file sorgente, test o punti di ingresso. Determina innanzitutto come fastfetch rappresenta e rileva i gestori di pacchetti supportati, quindi definisci quale gestore dovrebbe essere aggiunto e quale output o test dimostrerebbe il completamento.

Scritto dal modello di indicizzazione a partire dal testo della issue.