ci: ci: fix when sorted pr checks workflow is executed

[galargh]

Related Issues

#323 (comment)

Proposed Changes

Do not comment when the workflow_run that triggered the sorted PR checks workflow was itself triggered by events other than the pull request event.

Additional Info

The check for github.event.workflow_run.pull_requests[0] is not sufficient because there are PRs with lotus:master as head (e.g. DIGIIX-Ltd#323).

I disabled the workflow until this is merged.

Checklist

Before you mark the PR ready for review, please make sure that:

• Commits have a clear commit message.
• PR title is in the form of of <PR type>: <area>: <change being made>
  • example: fix: mempool: Introduce a cache for valid signatures
  • PR type: fix, feat, build, chore, ci, docs, perf, refactor, revert, style, test
  • area, e.g. api, chain, state, market, mempool, multisig, networking, paych, proving, sealing, wallet, deps
• If the PR affects users (e.g., new feature, bug fix, system requirements change), update the CHANGELOG.md and add details to the UNRELEASED section.
• New features have usage guidelines and / or documentation updates in
  • Lotus Documentation
  • Discussion Tutorials
• Tests exist for new functionality or change in behavior
• CI is green