BUG: no attribute 'base_url' on pitt_city_council

[bonfirefan]

Error message pasted below from @0x1F602 seems to be for linux as the tests ran okay on my mac:

platform linux -- Python 3.7.10, pytest-6.2.2, py-1.10.0, pluggy-0.13.1
rootdir: /home/server/Scripts/city-scrapers-pitt, configfile: setup.cfg
collected 384 items / 1 error / 383 selected

==================================== ERRORS ====================================
_______________ ERROR collecting tests/test_pitt_city_council.py _______________
tests/test_pitt_city_council.py:18: in <module>
    parsed_items = [item for item in spider.parse_legistar(test_response)]
tests/test_pitt_city_council.py:18: in <listcomp>
    parsed_items = [item for item in spider.parse_legistar(test_response)]
city_scrapers/spiders/pitt_city_council.py:37: in parse_legistar
    source=self._parse_source(event),
city_scrapers/spiders/pitt_city_council.py:82: in _parse_source
    default_source = "{}/Calendar.aspx".format(self.base_url)
E   AttributeError: 'PittCityCouncilSpider' object has no attribute 'base_url'
=============================== warnings summary ===============================```