Run workflows on pull_request event

[ilia1243]

Currently workflows are run on push event that restricts external contribution from forks. Need to run workflows on pull_request event and think of

• Avoid double runs
• Persist ability to run in branches without PR.

https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#pull_request https://docs.github.com/en/actions/managing-workflow-runs/approving-workflow-runs-from-public-forks https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/enabling-features-for-your-repository/managing-github-actions-settings-for-a-repository#controlling-changes-from-forks-to-workflows-in-public-repositories