Update actions/checkout action to v4

Author: renovate[bot]

.github/workflows/githubaction-comment-apply.yml

@@ -40,7 +40,7 @@ jobs:
       stack_changed: ${{ steps.filter.outputs.stack_changed }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0  # Important to fetch all history for branches