bpo-41325: Add version note for args and kwargs property in call object (GH-21525)

(cherry picked from commit 9b01c598ca)

Co-authored-by: Jordan Speicher <uSpike@users.noreply.github.com>

Doc/library/unittest.mock.rst

@@ -647,6 +647,9 @@ the *new_callable* argument to :func:`patch`.
         arguments and make more complex assertions. See
         :ref:`calls as tuples <calls-as-tuples>`.
 
+        .. versionchanged:: 3.8
+           Added ``args`` and ``kwargs`` properties.
+
 
     .. attribute:: call_args_list