Bump actions/checkout

Author: dylanhand

.github/workflows/docsygen.yml

@@ -21,7 +21,7 @@ jobs:
       name: github-pages
       url: ${{ steps.deploy.outputs.page_url }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           repository: giellalt/giellalt.github.io