Implement labelling for release notes and topics check (#71726)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/68459
Pull Request resolved: https://github.com/pytorch/pytorch/pull/71726
Reviewed By: malfet
Differential Revision: D33793084
Pulled By: atalman
fbshipit-source-id: 5840bff63c897f09e9d2d70ef435b8764c5d64c0
(cherry picked from commit dd6b3a1131913d2ad8b6dde18aabede3495adc29)
