How to associate workflow runs with pull request

I want to use Github API to find the workflow runs that are triggered by a particular pull requests, but this information isn’t include in GET /repos/{owner}/{repo}/pulls/{pull_number}.

I also tried to associate workflow runs and pr by searching through list of workflow runs, but for workflow runs that are triggered by forked pr, response of GET /repos/{owner}/{repo}/actions/runs/{run_id} has empty “pull_requests” attribute.

I am wondering if anyone know how to I can associate pull request with respective workflow runs? Thanks!