Clean-up CI warnings

[ekatef]

As discussed with @davide-f, it might be a good idea to clean warnings produced during CI workflow. The current list looks like following:

• Node.js 12 actions are deprecated. Please update the following actions to use Node.js 16: akhilmhdh/contributors-readme-action@v2.3.6. For more information see: https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/.
• The save-state command is deprecated and will be disabled soon. Please upgrade to using Environment Files. For more information see: https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/
• The set-output command is deprecated and will be disabled soon. Please upgrade to using Environment Files. For more information see: https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/
• Mamba support is still experimental and can result in differently solved environments!
• Upgrade setuptools version to > 65.5.1 to get rid of a vulnerability issue.

[davide-f]

This is likely no more relevant; we have CI warnings but #1172 is likely to drop most of those we are currently adopting, what do you think?

[ekatef]

This is likely no more relevant; we have CI warnings but #1172 is likely to drop most of those we are currently adopting, what do you think?

Agree. I suspect we may still have some pandas warnings even after #1172, but the list in this issue is definitely outdated. Closing! :D