Release notes issues

[anselmbradford]

Describe the bug
There are a few bugs in the release notes generation, which surfaced in 79d81d2:

• The Fixing legacy select… commit didn't get a bullet for some reason. This is a commit with a commit description, which is likely not handled correctly.
• The Add <cfpb-tagline> - commit doesn't escape the <cfpb-tagline> in the commit, so it looks blank when rendered in GitHub.
• The CFPBot commits should be ignored from the changelog.

To Reproduce

1. yarn changelog can be used to preview what the changelog will look like.