Fix lychee: add --root-dir for root-relative link resolution

Author: ronaldtse

.github/workflows/links.yml

@@ -35,7 +35,7 @@ jobs:
     - name: Link Checker
       uses: lycheeverse/lychee-action@v2
       with:
-        args: --verbose --no-progress -- _site/**/*.html
+        args: --verbose --no-progress --root-dir _site -- _site/**/*.html
         fail: true
       env:
         GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}