This leads to caching the tracebacks which can keep user's objects in local
namespaces alive indefinitely.  This can lead to very surprising memory issues
for users and will result in incorrect tracebacks.

Responsive to matplotlib#25406

This is to help prevent reference cycles between the frames and the locals in
that frame.

While garbage collection should in most cases take care of this eventually, we
can help the interpreter out and break the cycle before we return.