This updates all Python packages that download their source from PyPi to
use pypi.mk.

This will allow future improvements/changes to pypi.mk to affect all
relevant packages.

This also makes it easier for future Python packages to start using
pypi.mk, when it's clear how it is used in existing packages.

Signed-off-by: Jeffery To <jeffery.to@gmail.com>

Signed-off-by: Eneas U de Queiroz <cote2004-github@yahoo.com>

The defusedxml package contains several Python-only workarounds and
fixes for denial of service and other vulnerabilities in Python's XML
libraries. In order to benefit from the protection you just have to
import and use the listed functions / classes from the right defusedxml
module instead of the original module.

Currently, openpyxl detects, and uses defusedxml, if installed.

Signed-off-by: Eneas U de Queiroz <cote2004-github@yahoo.com>