to_glyphs_test: must define axes and source locations
to_glyphs_test: must define axes and source locations

the 'axes' element is now required since designspaceLib 3.27.
The 'location' element for the sources must be not None too, or else some unhandled TypeError occurs.
We shall investigate later...

googlefonts/glyphsLib,googlei18n/glyphsLib