Update changelog

CHANGELOG.rst

@@ -44,6 +44,10 @@ Bug fixes
 * Reorganised how ``Indicator`` subclasses can added arguments to the call signature. Injecting such arguments now works. For xclim's subclasses, this bug only affected the ``indexer`` argument of indicators subclassing ``xc.core.indicator.IndexingIndicator``. (:pull:`1981`).
 * All-nan slices are now treated correctly in method `ExtremeValues`. (:issue:`1982`, :pull:`1983`).
 
+New features and enhancements
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+* ``chill_unit`` now accepts a new argument `positive_only` to compute the daily positive chill units. (:pull:`2003`).
+
 v0.53.1 (2024-10-21)
 --------------------
 Contributors to this version: Trevor James Smith (:user:`Zeitsperre`).