This test is ran in the backend and, if we do not mark it as post
install, the dependencies of the web module are not installed.
The webclient will then errors like "View type 'kanban' is not present
in the view registry".
The `unittest2` package is simply a backport of `unittest` from the
Standard Library of Python 2.7 to previous versions.
There is no reason to use it any longer.
Closes#6941