Automatically run CI builds for external contributions

When an external contributor submits a PR, CI builds are on hold until manually authorized by a team member. This complicates external contributions as we won't know the build outcome for a long time. Is there a way to alleviate this pain?

PS: Out of curiosity, why did you choose CircleCI over GitHub Actions?

Start by reviewing the repository's CI configuration and the workflow that holds builds for external pull requests; no specific files or tests are named. Compare the current CircleCI authorization behavior with the proposed GitHub Actions alternative, and define done as safely obtaining build results without manual team-member authorization.

Written by the indexing model from the issue text.