[arch-general] Replace python-magic from darwinsys with ahupp implementation

Hi all! Current in pacman we have python-magic from http://darwinsys.com/file/ with an unknown custom license. We have other implementation with MIT license made by ahupp [1]. The second one is available in pypi and is more advanced that the first one. I have been checking the code of dependencies of python-magic and I can see that deepin-movie and diffoscope supports well ahupp version. Why not replace python-magic with diffoscope version, as can see in AUR [2] this version is used for much more packages. Greetings. [1]: https://github.com/ahupp/python-magic [2]: https://aur.archlinux.org/packages/python-magic-ahupp/ -- Óscar García Amor | ogarcia at moire.org | http://ogarcia.me