chore(deps): update actions/checkout digest to b684943

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@b6849436894e144dbce29d7d7fda2ae3bf9d8365
       - uses: articulate/actions-markdownlint@v1