Automate releasing more

[alexmojaki]

Currently to release a new version I have to:

1. Update generated stubs just in case it should have been done in a previous PR. Related: Update __init__.pyi after running rye run generate-stubs #469
2. Create a GitHub release draft with a new version number tag, generate release notes, and edit them to exclude irrelevant things like docs updates.
3. Add a new section to CHANGELOG.md with a title containing the version number tag and current date, and copy in the release notes.
4. Add a line to the end of the file that looks something like [v1.0.1]: https://github.com/pydantic/logfire/compare/v1.0.0...v1.0.1 but with the correct version number tags.
5. Update the version number in the two pyproject.toml files in the root and in logfire-api.
6. Push and merge a PR with these changes.
7. Publish the GitHub release draft.

This is very tedious. It can't be fully automated, but there's a lot of potential for improvement.