Fix trusted run stopping at commit flow due to pending checks

[bennekrouf]

What changed

• Modified the next_flow function in src/services/trusted.rs to handle cases where a pull request's checks are still pending.
• Updated the logic to ensure that the flow does not stop at the commit stage due to pending checks.
• Added tests to verify that a pull request with pending checks does not end the chain and that the review is scoped to the checked-out branch's own pull request.

Why

The previous implementation stopped every trusted run at the commit flow due to pending checks, even though a person is not expected to act on these checks. This change ensures that the flow continues to the review stage, where the diff can be reviewed while CI runs, and the merge rules already handle the refusal to merge on pending checks.

How to test

• Open the Commit and PR tab and ensure that a pull request with pending checks does not stop the flow.
• Verify that the review flow is scoped to the checked-out branch's own pull request by checking the pull request number in the review step.