spec: require glib2 >= 2.46
spec: require glib2 >= 2.46

After 7c54413559d14dc6b0dd99f8c3df0572b7d44540,
glib2 >= 2.46 is now required to build libdnf.

rpm-software-management/libdnf,edynox/libdnf,rpm-software-management/libdnf,rpm-software-management/libdnf,hughsie/libhif,Conan-Kudo/libhif,Conan-Kudo/libhif,rpm-software-management/libhif,edynox/libdnf,rpm-software-management/libhif,hughsie/libhif,hughsie/libhif,edynox/libdnf,rpm-software-management/libhif,edynox/libdnf,hughsie/libhif,Conan-Kudo/libhif,rpm-software-management/libhif,rpm-software-management/libdnf,Conan-Kudo/libhif