Bump actions/checkout from 5 to 6 (#48)

Author: dependabot[bot]

.github/workflows/main.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Stamp URL
       run: |
         echo '#!/usr/bin/env bash' > github-url.sh