Update mheap/github-action-required-labels action to v3

This PR contains the following updates:

Package	Type	Update	Change
mheap/github-action-required-labels	action	major	`v2` -> `v3`

⚠ Dependency Lookup Warnings ⚠

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Release Notes

mheap/github-action-required-labels

### [`v3`](https://togithub.com/mheap/github-action-required-labels/releases/tag/v3) [Compare Source](https://togithub.com/mheap/github-action-required-labels/compare/v2...v3) Tag that always points to the latest commit in the v3.x.x series of releases

Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

[ ] If you want to rebase/retry this PR, check this box

This PR has been generated by Renovate Bot.

JuulLabs / exercise