fix flake8 error

Author: andrewfulton9

zarr/tests/test_core.py

@@ -2407,4 +2407,3 @@ def test_hexdigest(self):
         z = self.create_array(shape=(1050,), chunks=100, dtype='<i4')
         z.attrs['foo'] = 'bar'
         assert '05b0663ffe1785f38d3a459dec17e57a18f254af' == z.hexdigest()
-