fix minor typo in run_test.py (#60055)
Summary:
Fixes typo in run_test.py for option use_specified_test_cases_by
Pull Request resolved: https://github.com/pytorch/pytorch/pull/60055
Reviewed By: walterddr
Differential Revision: D29150156
Pulled By: janeyx99
fbshipit-source-id: 375e594d09c83188bfa80762c8b833a0b7c5cca4
