fix: remove ppxlib 0.13.0, since a newer version is available
fix: remove ppxlib 0.13.0, since a newer version is available

Signed-off-by: Pau Ruiz Safont <9c4aad32b049b39a74875643d7fe76c19fd4f9a1@citrix.com>

xapi-project/xs-opam,lindig/xs-opam