GH Actions: Bump xt0rted/markdownlint-problem-matcher from 1 to 2

Bumps [xt0rted/markdownlint-problem-matcher](https://github.com/xt0rted/markdownlint-problem-matcher) from 1 to 2.
- [Release notes](https://github.com/xt0rted/markdownlint-problem-matcher/releases)
- [Changelog](https://github.com/xt0rted/markdownlint-problem-matcher/blob/main/CHANGELOG.md)
- [Commits](xt0rted/markdownlint-problem-matcher@v1...v2)

---
updated-dependencies:
- dependency-name: xt0rted/markdownlint-problem-matcher
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/markdown.yml

@@ -42,7 +42,7 @@ jobs:
 
       # @link https://github.com/marketplace/actions/problem-matcher-for-markdownlint-cli
       - name: Enable showing issue in PRs
-        uses: xt0rted/markdownlint-problem-matcher@v1
+        uses: xt0rted/markdownlint-problem-matcher@v2
 
       - name: Check markdown with CLI2
         run: markdownlint-cli2