workflows: bump actionshub/markdownlint from 2.1.2 to 3.1.3 (#1054)

Bumps [actionshub/markdownlint](https://github.com/actionshub/markdownlint) from 2.1.2 to 3.1.3.
- [Release notes](https://github.com/actionshub/markdownlint/releases)
- [Commits](actionshub/markdownlint@v2.1.2...v3.1.3)

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

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Author: dependabot[bot]

.github/workflows/pr-lint.yaml

@@ -20,4 +20,4 @@ jobs:
     name: PR - Markdownlint
     steps:
       - name: Run markdownlint
-        uses: actionshub/markdownlint@v2.1.2
+        uses: actionshub/markdownlint@v3.1.3