Add Felipe Artur as backend maintainer

Manager Justification

It's hard to specify hard requirements for becoming a maintainer, which is why the documentation consists of flexible guidelines. Reviewers are encouraged to think of their eligibility for maintainership in the terms of "I could be ready at any time to be a maintainer as long as my work as an author and reviewer is consistent with other maintainers".

• The MRs reviewed by the candidate consistently make it through maintainer review without significant additionally required changes.

• The MRs authored by the candidate consistently make it through reviewer and maintainer review without significant required changes.

• @felipe_artur has been part of GitLab for more than 6 years and got promoted to Senior Backend Engineer July 2021. He knows the standards of the codebase very well, and is very familiar with the review or development processes (and GitLab processes in general).

• He has authored more than 300 Merge requests and is an expert mostly in features related to Plan. These features share very often code with other components.

• He has approved more than 230 Merge requests

• Felipe went through the old trainee process, has his trainee maintainer issue opened.

• Examples of some good reviews:

  • Allow to update requirement status widget throu... (gitlab-org/gitlab!98313 - merged)
  • Add verification status widget for requirements (gitlab-org/gitlab!93114 - merged)
  • Add ability to remove a work item's parent with... (gitlab-org/gitlab!91494 - merged)
  • Search Page layout changes (gitlab-org/gitlab!97820 - merged)

Before Merging(Manager Tasks)

• Mention the maintainers from the given specialty and ask them to provide feedback directly on this merge request.
• Leave this merge request open for 1 week, to give the maintainers time to provide feedback.
• Ensure we have at least 2 approvals from existing maintainers.

Once This MR is Merged

1. Create an access request for maintainer access to gitlab-org/<project>.
2. Join the backend-maintainers slack group
3. Ask the maintainers in your group to invite you to any maintainer-specific meeting if one exists.
4. Let a maintainer add you to @gitlab-org/maintainers/rails-backend
5. Announce it everywhere
6. Keep reviewing, start merging 🤘 😎 🤘