Fix memory leak in Qt event loop integration (#14240)...
Fix memory leak in Qt event loop integration (#14240)
See:
https://github.com/ipython/ipython/issues/14240
- the QEventLoop, `event_loop`, is not deleted when exiting the scope as
passing `app` to the constructor parents the object to `app`. This
creates a memory leak as QEventLoop objects are being accumulated.
- issue reported by and fix suggested by @pag
