Automatically create a PR to update a repositories update.json file when publishing a release

[Standard8]

Now that releases can be automatically published to github (when enable-github-release: true), it would be useful if we could also generate a PR that creates an update to update.json when the release is published.

This would avoid the additional manual step of creating the PR.

Another option would be that I could create a github action for the repository, but it seems it might be better integrated into the existing CI.

The requirements would be:

• When a release is published to the repository, update the "version" and "update_link" fields in the update.json file.
  • Care should be taken to avoid updating fields with a strict_max_version - it isn't used at the moment, but might be in the future (xref https://extensionworkshop.com/documentation/manage/updating-your-extension/).
• Create a PR with the changes.

I'm suggesting to create a PR, so that the authors can do a final check before the add-on is released to everyone.