document the compress_level argument to tarfile.open (closes #21404)

Patch by Katherine Busch.
diff --git a/Misc/ACKS b/Misc/ACKS
index 9cf4572..571f1a6 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -195,6 +195,7 @@
 Alastair Burt
 Tarn Weisner Burton
 Lee Busby
+Katherine Busch
 Ralph Butler
 Nicolas Cadou
 Jp Calderone