As 18.04 just EOLed 2 weeks ago.

Fixes https://github.com/pytorch/pytorch/issues/81120

Pull Request resolved: https://github.com/pytorch/pytorch/pull/101301
Approved by: https://github.com/seemethere, https://github.com/atalman

(cherry picked from commit c772d56966574deee7b94d060ec77880f581b762)