added whatsnew note

Author: AbhishekChaudharii

doc/source/whatsnew/v3.0.0.rst

@@ -592,7 +592,6 @@ Performance improvements
 - Performance improvement in :meth:`RangeIndex.take` returning a :class:`RangeIndex` instead of a :class:`Index` when possible. (:issue:`57445`, :issue:`57752`)
 - Performance improvement in :func:`merge` if hash-join can be used (:issue:`57970`)
 - Performance improvement in :meth:`CategoricalDtype.update_dtype` when ``dtype`` is a :class:`CategoricalDtype` with non ``None`` categories and ordered (:issue:`59647`)
-- Performance improvement in :meth:`DataFrame.astype` when converting to extension floating dtypes, e.g. "Float64" (:issue:`60066`)
 - Performance improvement in :meth:`to_hdf` avoid unnecessary reopenings of the HDF5 file to speedup data addition to files with a very large number of groups . (:issue:`58248`)
 - Performance improvement in ``DataFrameGroupBy.__len__`` and ``SeriesGroupBy.__len__`` (:issue:`57595`)
 - Performance improvement in indexing operations for string dtypes (:issue:`56997`)
@@ -739,6 +738,8 @@ Reshaping
 - Bug in :meth:`DataFrame.unstack` producing incorrect results when ``sort=False`` (:issue:`54987`, :issue:`55516`)
 - Bug in :meth:`DataFrame.pivot_table` incorrectly subaggregating results when called without an ``index`` argument (:issue:`58722`)
 - Bug in :meth:`DataFrame.unstack` producing incorrect results when manipulating empty :class:`DataFrame` with an :class:`ExtentionDtype` (:issue:`59123`)
+- Bug in :meth:`DataFrame.merge` when merging two dataframes with column dtype as numpy.uintc resulting in KeyError: <class 'numpy.uintc'> ,Only on windows (:issue:`58713`)
+- Bug in :meth:`DataFrame.merge` when merging two dataframes with column dtype as numpy.intc resulting in ValueError: Buffer dtype mismatch, Only on windows (:issue:`60091`)
 
 Sparse
 ^^^^^^