Update actions/checkout action to v6 (#8695)

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

.github/workflows/nightly.yml

@@ -14,7 +14,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Trunk Check
         uses: trunk-io/trunk-action@v1
@@ -31,7 +31,7 @@ jobs:
       pull-requests: write # For trunk to create PRs
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Trunk Upgrade
         uses: trunk-io/trunk-action/upgrade@v1