Add missing EOF newline (fixing xrdb warning)

This is fixing `xrdb` warning when applying `xresources` (see below).     

    $ xrdb -merge base16-3024.dark.xresources
    /home/miro/src/base16-xresources/base16-3024.dark.xresources:39: warning: End of input with no newline, supplemented newline
        *.color15:      base07