ci(*:skip) Add Javier as codeowner to /benchmarks

[tanertopal]

Issue

Description

This makes Javier a codeowner for the /benchmarks directory.

Related issues/PRs

Proposal

Explanation

Checklist

• [ ] Implement proposed change
• [ ] Write tests
• [ ] Update documentation
• [ ] Make CI checks pass
• [ ] Ping maintainers on Slack (channel #contributions)

Any other comments?