Bump actions/checkout@v4 for website

note: cannot use checkout@v4 for testsuite
probably need to rebuild the docker container
for the perl-compiler.

.github/workflows/website.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
       with:
         submodules: true  # Fetch Hugo themes (true OR recursive)
         fetch-depth: 0    # Fetch all history for .GitInfo and .Lastmod