feat: add some additional GitHub Actions outputs

Description

Using the GitHub action, python-semantic-release/python-semantic-release@v#.#.#, we should set some environment variables for later stages to use. For example:

  • release created Implemented as 'released'
  • old previous_version
  • new version Implemented as 'version'
  • release_notes
  • release link

Use cases

Later stages could use this information such as if there's a need to publish to repos beyond what is built in.

Possible implementation

I haven't looked at GitHub action syntax, but this seems like we can gather all the info easily even with existing command options and just populate or document the environment variables.
Compare with JS semantic release.