Be bold: prefer pip over easy_install

[qsqa]

At https://packaging.python.org/discussions/pip-vs-easy-install/, it would be helpful to note that easy_install is now deprecated.

[webknjaz]

@qsqa That's a good idea. Feel free to send a PR modifying https://github.com/pypa/packaging.python.org/blob/main/source/discussions/pip-vs-easy-install.rst.