fixes clang-tidy-11 install by using ubuntu18.04 instead of 20.04 (#51725)
Summary:
Fixes #{issue number}
Pull Request resolved: https://github.com/pytorch/pytorch/pull/51725
Reviewed By: walterddr
Differential Revision: D26255539
Pulled By: janeyx99
fbshipit-source-id: 1b4459e0c474938c134c529501c6c04106d5b18e
