Add new team members on the reviewer list

[atheo89]

Description

This PR adds the new team members to the reviewers list on notebooks repo.

Welcome folks :)

How Has This Been Tested?

Merge criteria:

• [ ] The commits are squashed in a cohesive manner and have meaningful messages.
• [ ] Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• [ ] The developer has manually tested the changes and verified that the changes work

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

Approval requirements bypassed by manually added approval.

This pull-request has been approved by: caponetto, jiridanek

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Needs approval from an approver in each of these files: - **[OWNERS](https://github.com/opendatahub-io/notebooks/blob/main/OWNERS)** Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment