Upgrading setuptools fails due to conflict with system install python-setuptools

I've run into cases where upgrading setuptools (via the `python_upgrade_packaging_tools` role variable) fails, I believe due to conflicts with the existing `python-setuptools` package installed with apt. Similar issues have been filed against pip: https://github.com/pypa/pip/issues/2438, https://github.com/pypa/pip/issues/2545
