Added a migration for greek language
Added a migration for greek language

Greek language became a choice in FlatpageTranslation

alper/volunteer_planner,pitpalme/volunteer_planner,klinger/volunteer_planner,pitpalme/volunteer_planner,volunteer-planner/volunteer_planner,coders4help/volunteer_planner,volunteer-planner/volunteer_planner,coders4help/volunteer_planner,klinger/volunteer_planner,pitpalme/volunteer_planner,christophmeissner/volunteer_planner,coders4help/volunteer_planner,christophmeissner/volunteer_planner,alper/volunteer_planner,alper/volunteer_planner,klinger/volunteer_planner,pitpalme/volunteer_planner,coders4help/volunteer_planner,volunteer-planner/volunteer_planner,volunteer-planner/volunteer_planner,christophmeissner/volunteer_planner,christophmeissner/volunteer_planner,klinger/volunteer_planner