pip should point to pip3 in docker

This causes a problem building the drools-pdp
image, failing the actual merge operation and
pushing a new image.

Issue-ID: POLICY-2181
Signed-off-by: jhh <jorge.hernandez-herrero@att.com>
Change-Id: Ibd6e3ddf469d4e56d330450fb2064200ce504740
1 file changed