Updater - Bullet-point resolution doesn't work if there's plain introductory test #120

In case there's a non-bullet-point text in the existing changelog.md, the update-changelog.ps1 logic that decides what kind of bullet points are in use doesn't recognize them correctly.

Example: https://github.com/getsentry/github-workflows/blob/de9e3fa91db31c70cc49cc2d92e980e0459feb2f/CHANGELOG.md causes no bullet points