Bump version to 1.5.0, 1.4.x is on flatpak-1.4.x branch
Bump version to 1.5.0, 1.4.x is on flatpak-1.4.x branch

matthiasclasen/flatpak,matthiasclasen/flatpak,flatpak/flatpak,matthiasclasen/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak