[#2124] fix(python): add missing unitest lib

[xael-fry]

lighthouse #2124

[asolntsev]

@xael-fry Do I correctly understand that you want to add some 3rd-party Python testing framework to Play?

Is it really a good idea?

• Can't we just "import" this library (like we add dependencies in Java projects)?
• Who will be responsible for keeping this library up-to-date?

[xael-fry]

It is not a 3rd-party lib, it is an optional module of python 2.7 present in installer.
So I don see any problem here

[asolntsev]

@xael-fry I still don't understand :)
But if you don't see problems, we can merge it.

[xael-fry]

The lib was present before, but I accidentally remove it wen updating python.
As it is a Python package lib, we just need to keep update python