Add delay between approving and merging PR in the automated PRs manager

[sgalsaleh]

Description, Motivation and Context

Merging PRs occasionally fails due to some race condition. I believe this might fix the issue.

Checklist

• [ ] New and existing tests pass locally with introduced changes.
• [ ] Tests for the changes have been added (for bug fixes / features)
• [ ] The commit message(s) are informative and highlight any breaking changes
• [ ] Any documentation required has been added/updated. For changes to https://troubleshoot.sh/ create a PR here

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No