add whatsnew for GH-29403

Author: nathalier

doc/source/whatsnew/v1.0.0.rst

@@ -469,6 +469,7 @@ Datetimelike
 - Bug in :func:`pandas._config.localization.get_locales` where the ``locales -a`` encodes the locales list as windows-1252 (:issue:`23638`, :issue:`24760`, :issue:`27368`)
 - Bug in :meth:`Series.var` failing to raise ``TypeError`` when called with ``timedelta64[ns]`` dtype (:issue:`28289`)
 - Bug in :meth:`DatetimeIndex.strftime` and :meth:`Series.dt.strftime` where ``NaT`` was converted to the string ``'NaT'`` instead of ``np.nan`` (:issue:`29578`)
+- Bug in :func:`pandas.core.tools.datetimes.should_cache` raising ``TypeError`` when trying to get a slice of a deque (:issue:`29403`)
 
 Timedelta
 ^^^^^^^^^