Firefox x-scheme-handler/ftp should be removed from .desktop

[Ahmad Samir]

Hello.

Firefox disabled support for FTP in 88.0: https://www.mozilla.org/en-US/firefox/88.0/releasenotes/

And removed it in 90.0: https://www.mozilla.org/en-US/firefox/90.0/releasenotes/

Posting here because this mimetype actually causes some interference for KIO url handling: 
https://invent.kde.org/frameworks/kio/-/merge_requests/570#note_300103


Since FTP support happens to be gone, could you please change firefox.desktop?

-- 
Ahmad Samir