Set up version tagging and automated release notes workflows

[jonikorpi]

• Create a git tag for each version change
• Compile release notes out of commit messages for each new version, and put them somewhere visible. Probably best done as a GitHub Release?
• Make sure the features above are implemented as simply as possible. I’ve had both of these in another open-source project in the past, but the GitHub workflows powering them broke by themselves over time and became a huge burden to fix. This time I need them to just work, and be blindingly easy to maintain.