chore(deps): update actions/checkout digest to 6b42224

Author: renovate[bot]

.github/workflows/markdown-lint.yml

@@ -35,5 +35,5 @@ jobs:
   markdown-lint:
     runs-on: ubuntu-22.04
     steps:
-      - uses: actions/checkout@44c2b7a8a4ea60a981eaca3cf939b5f4305c123b
+      - uses: actions/checkout@6b42224f41ee5dfe5395e27c8b2746f1f9955030
       - uses: articulate/actions-markdownlint@v1