Make fcatteau a maintainer of container-scanning

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.
  • gitlab-org/security-products/analyzers/container-scanning!2991 (merged)
  • gitlab-org/security-products/analyzers/container-scanning!2989 (merged)
• The MRs authored by the candidate consistently make it through reviewer and maintainer review without significant required changes.
  • Fabien hasn't made significant contributions to the project, but has steered it and initiated updates that a maintainer would typically do; e.g.:
  • gitlab-org/security-products/analyzers/container-scanning!2947 (merged)
  • gitlab-org/security-products/analyzers/container-scanning!2824 (merged)
  • gitlab-org/security-products/analyzers/container-scanning!2745 (closed)
  • gitlab-org/security-products/analyzers/container-scanning!2940 (merged)

Before Merging (Manager Tasks)

• Close any relevant trainee maintainer issues with a comment indicating that this merge request is being created, as (they are no longer required to become a maintainer).
• Mention the maintainers from the given specialty with the template below.
• 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.

Template call to action

SPECIALITY Maintainers, please review this proposal to make TRAINEE maintainer of PROJECT. 

* If you have blocking feedback adhering [to the documentation](https://about.gitlab.com/handbook/engineering/workflow/code-review/#how-to-become-a-project-maintainer) please share it with me via Slack.
* If you are in agreement, and can vouch for this proposal, please approve.

After 1 week, if there is no blocking feedback and at least 2 approvals, I will merge this MR.

Once This MR is Merged

1. Let a maintainer add you to @gitlab-org/maintainers/container-scanning with Owner access level.
2. Announce it everywhere
3. Keep reviewing, start merging 🤘 😎 🤘