[Workflows] add a more secure way to run tests from a PR. (#7969)
* add a more secure way to run tests from a PR.
* make pytest more secure.
* address dhruv's comments.
* improve validation check.
* Update .github/workflows/run_tests_from_a_pr.yml
Co-authored-by: Dhruv Nair <dhruv.nair@gmail.com>
---------
Co-authored-by: Dhruv Nair <dhruv.nair@gmail.com>