Add glib2-devel to Arch dependencies to satisfy appstream

Arch recently separated glib2 in two and if glib2-devel is not installed, appstream will fail to build with an error src/meson.build:150:23: ERROR: Dependency 'glib-2.0' tool variable 'glib_mkenums' contains erroneous value: '/usr/bin/glib-mkenums'

The following email was sent on the Arch developer mailing list

Thanks to Fabian, as of 2.80.3-1, the development utilities requiring additional dependencies (python, python-packaging, libelf) have been split from glib2 into glib2-devel with proper depends.

You may need to add glib2-devel to the makedepends of your packages to get them to build again. At the same time, consider removing python or python-packaging from the makedepends if they were only added to run gdbus-codegen, glib-genmarshal or glib-mkenums.

More information on Arch Gitlab https://gitlab.archlinux.org/archlinux/packaging/packages/glib2/-/issues/7