Use venv module for PROJECT_VENV building

Currently, if USE_VENV=True, PROJECT_VENVs are initialized using the
tools/build_venv.sh script; this script depends on the virtualenv
module, which is much less commonly available than the built-in venv
module which we already use many places.

This changes the build_venv.sh script to use `python -m venv` instead.

Needed-By: https://review.opendev.org/c/openstack/ironic/+/930776
Change-Id: I89fa2c0c4261e715064e77a766d98a34299532b3
1 file changed