added new line which was removed accidentally

Author: ShisuiUzumaki

doc/source/whatsnew/v2.0.0.rst

@@ -509,6 +509,7 @@ Deprecations
 ~~~~~~~~~~~~
 - Deprecated argument ``infer_datetime_format`` in :func:`to_datetime` and :func:`read_csv`, as a strict version of it is now the default (:issue:`48621`)
 - :meth:`Index.is_categorical` has been deprecated. Use :func:`pandas.api.types.is_categorical_dtype` instead (:issue:`50042`)
+
 .. ---------------------------------------------------------------------------
 
 .. _whatsnew_200.prior_deprecations: