Remove _reset_warning_registry (#38485)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/38485
Python 2 has reached end-of-life and is no longer supported by PyTorch.
This class does nothing in Python 3.
Test Plan: CI
Reviewed By: ailzhang
Differential Revision: D21575260
Pulled By: dreiss
fbshipit-source-id: 184696c9fa501e8d2517950b47cdbc90b2ae8053
