bpo-32424: Improve test coverage for xml.etree.ElementTree (GH-12891)

* Fix typo in test_cyclic_gc subtest
* Improve test coverage for xml.etree.ElementTree
diff --git a/Misc/ACKS b/Misc/ACKS
index 393ea20..300e788 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -647,6 +647,7 @@
 Thomas Heller
 Malte Helmert
 Lance Finn Helsten
+Gordon P. Hemsley
 Jonathan Hendry
 Nathan Henrie
 Michael Henry