remove no-longer necessary

Author: jbrockmendel

pandas/tests/tseries/holiday/test_holiday.py

@@ -321,7 +321,7 @@ def test_holidays_with_timezone_specified_but_no_occurences():
     # GH 54580
     # _apply_rule() in holiday.py was silently dropping timezones if you passed it
     # an empty list of holiday dates that had timezone information
-    start_date = Timestamp("2018-01-01", tz="America/Chicago").as_unit("ns")
+    start_date = Timestamp("2018-01-01", tz="America/Chicago")
     end_date = Timestamp("2018-01-11", tz="America/Chicago")
     test_case = USFederalHolidayCalendar().holidays(
         start_date, end_date, return_name=True