[hotfix] Always use main branch website to deploy documentation

The website/* in release-xx branch is not up-to-date, and may cause problems if deploying documentation using release-xx branches.

Author: wuchong

.github/workflows/docs-deploy.yaml

@@ -29,6 +29,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
+          ref: main
           fetch-depth: 0
       - name: Generate versioned docs
         run: ./build_versioned_docs.sh