Update xt0rted/markdownlint-problem-matcher action to v3

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
xt0rted/markdownlint-problem-matcher	action	major	v2 -> v3

---

Release Notes

xt0rted/markdownlint-problem-matcher (xt0rted/markdownlint-problem-matcher)

### [`v3`](https://togithub.com/xt0rted/markdownlint-problem-matcher/compare/v2...v3) [Compare Source](https://togithub.com/xt0rted/markdownlint-problem-matcher/compare/v2...v3)

---

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 Mend Renovate. View repository job log here.