DOC: mention pandas-dev#14641 in 0.20.0 whatsnew

Author: jzwinck

doc/source/whatsnew/v0.20.0.txt

@@ -921,3 +921,4 @@ Bug Fixes
 - Bug in ``pd.melt()`` where passing a tuple value for ``value_vars`` caused a ``TypeError`` (:issue:`15348`)
 - Bug in ``.eval()`` which caused multiline evals to fail with local variables not on the first line (:issue:`15342`)
 - Bug in ``pd.read_msgpack`` which did not allow to load dataframe with an index of type ``CategoricalIndex`` (:issue:`15487`)
+- Use of ``np.finfo()`` during `import pandas` removed to mitigate deadlock on Python GIL misuse (:issue:`14641`)