chore(deps): update actions/checkout action to v6 (#5492)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

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

@@ -9,7 +9,7 @@ jobs:
     name: Check all links
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Restore lychee cache
         uses: actions/cache@v4

.github/workflows/lint-and-test.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Install Node.js and use yarn
         uses: actions/setup-node@v6