(main) Test artifacts signature in CI

[abelsromero]

What kind of change does this PR introduce? (check at least one)

• [ ] Bugfix
• [ ] Feature
• [ ] Documentation
• [ ] Refactor
• [x] Build improvement
• [x] Other (please describe)
  • Remove release risks by running parts of it alongside other tests :safety_vest:
  • Experiment to eventually automate the whole release process :rocket:

What is the goal of this pull request?

Test the signature of artifacts in CI.

Are there any alternative ways to implement this?

Yes, regarding where and how to store the keys. In the end, I decided to put them in the same code for reasons (it's a test key after all):

1. Simpler, all resides in one place.
2. Secrets don't work in PRs and I even had issues when setting environment variables in my fork (always empty :shrug:).

Are there any implications of this pull request? Anything a user must know?

no

Is it related to an existing issue?

- [ ] Yes - [x] No *Finally, please add a corresponding entry to CHANGELOG.adoc*