revert no-longer-necessary

Author: jbrockmendel

pandas/_testing/asserters.py

@@ -967,9 +967,6 @@ def assert_series_equal(
 
         # datetimelike may have different objects (e.g. datetime.datetime
         # vs Timestamp) but will compare equal
-        # TODO: this works for object-vs-dt64 but not e.g. dt64[ns] vs dt64[us],
-        #  which AFAICT would have been intended at the time
-        #  check_datetimelike_compat was implemented, xref GH#55638
         if not Index(left._values).equals(Index(right._values)):
             msg = (
                 f"[datetimelike_compat=True] {left._values} "