Update actions/checkout action to v5

Author: renovate[bot]

.github/workflows/markdown-link-check.yml

@@ -11,5 +11,5 @@ jobs:
   markdown-link-check:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4.2.1
+    - uses: actions/checkout@v5.0.1
     - uses: gaurav-nelson/github-action-markdown-link-check@1.0.15