plugin.py: Redirect DEBUG from `__del__` to `sys.stderr`
Description
As per #760 (closed) the Plugin.__del__() special method writes a DEBUG statement to stdout with print().
This replaces that with a sys.stderr.write()
Changes proposed in this merge request:
- Replace
printwithsys.stderr.writeinPlugin.__del__
This merge request, when approved, will address #760 (closed)