Tracker kit: Fix memory leak

Like moveList and copyList, duplicateList could be deleted here.
Pointed out by Clang static analyzer.

Change-Id: Ic80181af960bc8eb759449ea5719e9a439a877a0
Reviewed-on: https://review.haiku-os.org/c/haiku/+/1996
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

src/kits/tracker/FSClipboard.cpp

@@ -513,6 +513,7 @@ FSClipboardPaste(Model* model, uint32 linksMode)
 		// there was some problem with our target, so we bail out here
 		delete moveList;
 		delete copyList;
+		delete duplicateList;
 		return false;
 	}