prepare initial release

[tgolsson]

Release checklist:

• [x] Upon needing a release, create a PR:

  • [x] Update CHANGELOG.md to ensure it contains all relevant changes.
  • [x] Based on the above changes, set a new version in pyproject.toml.
  • [x] Replace the heading in the changelog
  • [x] Add diff labels at the bottom.

• [x] Pull the new main, and tag it with git tag -a vNEW_VERSION COMMIT_HASH.

• [ ] Push the tag with git push vNEW_VERSION

• [ ] Make a new PR that adds back the "Unreleased" heading in the changelog.

Most already done before; this just fixes the date and version in the pyproject.toml