Test failure in 2.9.0 release
Yeah, it's fixed.
```
======================================================================
ERROR: test_create_or_get (playhouse.tests.test_gfk.GFKTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/build/python-peewee/src/peewee/playhouse/tests/test_gfk.py", line 123, in test_create_or_get
    self._test_get_create(Tag.create_or_get)
AttributeError: type object 'Tag' has no attribute 'create_or_get'

----------------------------------------------------------------------
Ran 598 tests in 5.246s

FAILED (errors=1)
```