Add pip/pipx

[Cenness]

Add python package managers.
Despite their name pip and pipx are not limited to python and allow to distribute bare binaries via wheels.
https://news.ycombinator.com/item?id=31776873

Examples in the wild:
https://github.com/PyO3/maturin#usage
https://github.com/samwillis/nodejs-pypi#install

[sigoden]

Upt only supports os-level package management tools.
Upt will not support program-language-level package management tools like npm, gem, pip(x)...