fix: header seperator count

[zkoppert]

Pull Request

fixes #176

Proposed Changes

This pull request fixes the functionality of the write_to_markdown function in stale_repos.py and its corresponding tests in test_stale_repos.py. The main changes involve the proper handling of recently added optional metrics ("Days Since Last Release" and "Days Since Last PR") in the markdown output and the corresponding updates in the test cases.

Readiness Checklist

Author/Contributor

• If documentation is needed for this change, has that been included in this pull request
• run make lint and fix any issues that you have introduced
• run make test and ensure you have test coverage for the lines you are introducing
• If publishing new data to the public (scorecards, security scan results, code quality results, live dashboards, etc.), please request review from @jeffrey-luszcz

Reviewer

• Label as either fix, documentation, enhancement, infrastructure, maintenance or breaking