As it is commonly known, Python2 reaches its EOL in 2020.
For this reason, many distributions massively drop Python2
packages.

Certmonger utilizes by itself only python-dbus (among standard modules) and only at
build time for testing. With some help of 2to3 utility
several tests helpers have been migrated to Python3:
- converts the print statement to the print() function (reindented)
- remove u"..." literals
- remove Integer literals l and L
- change shebang to python3

TODO: migrate examples of helpers.

Fixes: https://pagure.io/certmonger/issue/138