Update link for vips-gmic
Update link for vips-gmic

vips-gmic doesn't appear to be a libvips repo anymore.
lovell/libvips,jcupitt/libvips,jcupitt/libvips,jcupitt/libvips,jcupitt/libvips,lovell/libvips,lovell/libvips,lovell/libvips