Fix pypi build and upload.

No need for job to create its own
venv like this.
virtualenv -p python3 /tmp/pypi

this does not update virtualenv first
also it was failing, I think due to
needing a readline package update.

python3 -m venv is preferred.
however we have lf-env.sh, which does things properly.
se we are going to use it.

Issue-ID: IT-20528
Signed-off-by: Aric Gardner <agardner@linuxfoundation.org>
Change-Id: If2b8369296256368659c41e9e77231d4442f55bd