[3.8] bpo-43882 - Mention urllib.parse changes in Whats new section. (#26277)

Author: orsenthil

Doc/whatsnew/3.8.rst

@@ -2294,4 +2294,16 @@ for and build on the oldest version in the range.
 with fixes by FX Coudert and Eli Rykoff, and backported to 3.8 by Maxime Bélanger
 and Ned Deily)
 
+Notable changes in Python 3.8.10
+================================
+
+urllib.parse
+------------
+
+The presence of newline or tab characters in parts of a URL allows for some
+forms of attacks. Following the WHATWG specification that updates :rfc:`3986`,
+ASCII newline ``\n``, ``\r`` and tab ``\t`` characters are stripped from the
+URL by the parser in :mod:`urllib.parse` preventing such attacks. The removal
+characters are controlled by a new module level variable
+``urllib.parse._UNSAFE_URL_BYTES_TO_REMOVE``. (See :issue:`43882`)