chore(CD): Fix automated release notes

[gmaclennan]

Release notes generated by npm run release-notes are incorrect, they include notes from before the previous release. This is probably due to the git-flow branching model we use, and conventional-changelog not recognizing the most recent commit.

This can cause release notes generation for Github releases to fail, because the release notes are too large to store in an environment variable. You will see the error in the Github release notes if this happens:

environment var (RELEASE_DESCRIPTION) value too large - rejected

An alternative option would be to encourage all pull requests to add a line to the release notes manually, and we could enforce this with a Github action. We have also discussed writing some end-user-friendly release notes (translated) that are distributed with the app, so the user can see them when upgrading.