Install build requirements in pre_build_script.sh (#3466)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/3466

Manually install build requirements because `python setup.py
bdist_wheel` does not install them.

imported-using-ghimport

Test Plan: Imported from OSS

Reviewed By: mikekgfb

Differential Revision: D56857485

Pulled By: dbort

fbshipit-source-id: f8b7db196074003078508b3a2ebbbedfe58b42d0