I'd like to propose add a `--upgrade` to venv module to automatically update pip and potentially setuptools if supplied. This will allow ensuring you have the latest and greatest of these core components.

Example Usage:
python3 -m venv --upgrade /tmp/awesome_venv

This will allow me to skip my next command that I usually always do:
/tmp/awesome_venv/bin/pip install --upgrade pip setuptools

Thoughts? If people are happy, I will look at doing the PR. 

I would envision I'll either import (which seems to be a no no from pip maintainers) the upgrade code or just fork pip ...