common: Fix memory leak in flatpak_number_prompt
common: Fix memory leak in flatpak_number_prompt

Closes: #1206
Approved by: alexlarsson

handsome-feng/flatpak,handsome-feng/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,handsome-feng/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,handsome-feng/flatpak,matthiasclasen/flatpak,flatpak/flatpak,handsome-feng/flatpak,flatpak/flatpak,matthiasclasen/flatpak