Revert D33409880: [pytorch][PR] Deprecating Python 3.6
Test Plan: revert-hammer
Differential Revision:
D33409880 (https://github.com/pytorch/pytorch/commit/d95be995617010c033252b46d96b5148e8ff1fa7)
Original commit changeset: 4f9123398960
Original Phabricator Diff: D33409880 (https://github.com/pytorch/pytorch/commit/d95be995617010c033252b46d96b5148e8ff1fa7)
fbshipit-source-id: 32dc1c3c07ef99a04fab7d0fb742cf4e6c4b718a
