Fix the Flatpak build manifest
There's no need for a Makefile, now that Flatpak has the "simple" buildsystem.
In addition, Meld requires Python 3, so let's move the Flatpak build to that.
There's no need for a Makefile, now that Flatpak has the "simple" buildsystem.
In addition, Meld requires Python 3, so let's move the Flatpak build to that.