Tiny fix

Author: h-vetinari

pandas/tests/test_strings.py

@@ -3103,6 +3103,6 @@ def test_method_on_bytes(self):
         lhs = Series(np.array(list('abc'), 'S1').astype(object))
         rhs = Series(np.array(list('def'), 'S1').astype(object))
 
-        result = lhs.str.cat(rhs, join='left')
+        result = lhs.str.cat(rhs)
         expected = Series(np.array(['ad', 'be', 'cf'], 'S2').astype(object))
         tm.assert_series_equal(result, expected)