[PRQ#52607] Deletion Request for mono42

MarsSeed [1] filed a deletion request for mono42 [2]: Unneeded legacy package from 2016. Fails to build on current Arch Linux. No other AUR package requires this. Safe to delete. [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/mono42/