add whatsnew entry

Author: ruimamaral

doc/source/whatsnew/v3.0.0.rst

@@ -370,8 +370,10 @@ Numeric
 
 Conversion
 ^^^^^^^^^^
+- Bug in :class:`Series` constructor responsible for bad datetime to str dtype conversions in ``read_csv``. (:issue:`57512`)
 - Bug in :meth:`DataFrame.update` bool dtype being converted to object (:issue:`55509`)
 - Bug in :meth:`Series.astype` might modify read-only array inplace when casting to a string dtype (:issue:`57212`)
+
 - Bug in :meth:`Series.reindex` not maintaining ``float32`` type when a ``reindex`` introduces a missing value (:issue:`45857`)
 
 Strings