update test

Author: jbrockmendel

Diff for: pandas/tests/reshape/test_cut.py

@@ -468,10 +468,6 @@ def test_datetime_cut(unit, box):
     data = box(data)
     result, _ = cut(data, 3, retbins=True)
 
-    if box is list:
-        # We don't (yet) do inference on these, so get nanos
-        unit = "ns"
-
     if unit == "s":
         # TODO: should we round to 7 seconds or 8?
         left = DatetimeIndex(