Fix bug in upgrader generation in mobile (#71578)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/71578
Use more robust way of extracting upgrader min and max versions
Test Plan: omgitsgreen
Reviewed By: cccclai
Differential Revision: D33690113
fbshipit-source-id: 79a964acb26d7ca1354e104710a285b8da3f46d1
(cherry picked from commit 9e316ee5c12e7bce9b17edebec2eeb38ecabd336)
