Exclude the 'tests' directory from find_packages in setup.py

[jeancochrane]

Overview

Previously, find_packages() didn't exclude the tests dir, which would cause pip to install the package under the the name tests when installing this . (We introduced this change in v1.0 when we switched from specifying councilmatic_core as the package to find_packages()).

Exclude the tests dir from packaging to prevent ImportErrors when trying to run tests in dependent packages.

Testing instructions

Test this change by testing datamade/django-councilmatic-notifications#33:

• cd to django-councilmatic-notifications
• Install your local version of django-councilmatic-notifications (with test dependencies) with pip install -e .[tests]
• Install this version of django-councilmatic, either by running:

pip install /path/to/local/django-councilmatic

or

pip install git+https://github.com/datamade/django-councilmatic@feature/jfc/remove-tests-from-find-packages

• Run pytest and confirm tests run normally

[hancush]

a+ spelunking, a+ fix! thanks, @jeancochrane :-)