[PRQ#48907] Deletion Request for gtkmm3-plplot-git

MarsSeed [1] filed a deletion request for gtkmm3-plplot-git [2]: Defunct bindings library VCS package for gtkmm3 from 2017. Upstream requires gtkmm4 now. Safe to delete, as it is broken and nothing depends on it. [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/gtkmm3-plplot-git/