python/pypillowfight: Disable tests entirely

This is getting entirely different results on i686-linux:

https://hydra.nixos.org/build/45122757/nixlog/6/raw

According to @jflesch the reference system these tests are built for is
Debian GNU/Linux (possibly only x86_64-linux I guess):

https://github.com/jflesch/libpillowfight/issues/2#issuecomment-268259174



So let's disable them until they're more deterministic and less
platform/distro-specific.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>