Bump DavidAnson/markdownlint-cli2-action from 19 to 20 (#306)

Bumps [DavidAnson/markdownlint-cli2-action](https://github.com/davidanson/markdownlint-cli2-action) from 19 to 20.
- [Release notes](https://github.com/davidanson/markdownlint-cli2-action/releases)
- [Commits](DavidAnson/markdownlint-cli2-action@v19...v20)

---
updated-dependencies:
- dependency-name: DavidAnson/markdownlint-cli2-action
  dependency-version: '20'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/lint.yml

@@ -39,7 +39,7 @@ jobs:
         args: -color
 
     - name: Lint markdown
-      uses: DavidAnson/markdownlint-cli2-action@v19
+      uses: DavidAnson/markdownlint-cli2-action@v20
       with:
         config: '.markdownlint.json'
         globs: |