Add Lior Lieberman and Mattia Lavacca as GEP Reviewers

[shaneutt]

What type of PR is this?

/kind documentation

What this PR does / why we need it:

@mlavacca and @LiorLieberman have both graciously agreed to help out with the GEP review cycles, as such we're promoting them both to GEP reviewers! Thank you @LiorLieberman and @mlavacca we appreciate your continued contributions to the project! 🙇

/cc @youngnick @robscott

[k8s-ci-robot]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[k8s-ci-robot]

Adding the "do-not-merge/release-note-label-needed" label because no release-note block was detected, please follow our release note process to remove it.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: shaneutt

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [shaneutt]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[robscott]

Thanks @LiorLieberman and @mlavacca!

/lgtm