setup.py: don't install tests
setup.py: don't install tests

Now that the tests directory has a __init__.py and is a Python package
find_packages() returns it and setup() will install it.

Instead of using find_packages() hardcode the list of included packages.

pexip/pygobject,pexip/pygobject,GNOME/pygobject,GNOME/pygobject,pexip/pygobject,GNOME/pygobject