Update all Python packages with pip.

pip-upgrade-all.py

# python pip-upgrade-all.py
#
# This file will upgrade all Python packages that are out of date.
#
# This file is a snippet from a Stack Overflow answer.
# Link: https://stackoverflow.com/a/5839291/9591441

import pkg_resources as pkg_res
from subprocess import call

packages = [package.project_name for package in pkg_res.working_set]

call('pip install --upgrade ' + ' '.join(packages), shell=True)