Ensure that plistlib doesn't corrupt deeply nested datastructures

Without this changeset plistlib would write empty tags for plistlib.Data
objects in deeply nested datastructures.

Fixes #17353
diff --git a/Misc/NEWS b/Misc/NEWS
index 8b0bce4..9804b0e 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -28,6 +28,8 @@
 Library
 -------
 
+- Issue #17353: Plistlib emitted empty data tags with deeply nested datastructures
+
 - Issue #11714: Use 'with' statements to assure a Semaphore releases a
   condition variable.  Original patch by Thomas Rachel.