run_tests.yml: revert to use regex instead of GitHub API
run_tests.yml: revert to use regex instead of GitHub API

because GitHub API has very low rate limit if not autheticated. Autheticate for the sake of using GitHub API doesn't feel right.

While using the API sounds more stable, the regex approach has been used since 2016 without a hiccup. c.f. https://github.com/ickc/pancritic/issues/13

sergiocorreia/panflute