Issue #21321: itertools.islice() now releases the reference to the source iterator when the slice is exhausted.

Patch by Anton Afanasyev.
diff --git a/Misc/ACKS b/Misc/ACKS
index 2d08627..c8c3880 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -17,6 +17,7 @@
 David Abrahams
 Marc Abramowitz
 Ron Adam
+Anton Afanasyev
 Ali Afshar
 Nitika Agarwal
 Jim Ahlstrom