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

Author: renovate[bot]

.github/workflows/publish_gh_pages.yml

@@ -23,7 +23,7 @@ jobs:
       url: ${{ steps.deployment.outputs.page_url }}
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Configure Pages
         uses: actions/configure-pages@v5
       - name: Install Node.js