refactor: add main branch back into the should-vercel-build script.

Author: lilingxi01

website/should-preview.sh website/should-vercel-build.shwebsite/should-preview.sh renamed to website/should-vercel-build.sh

@@ -3,7 +3,7 @@
 echo "VERCEL_GIT_COMMIT_REF: $VERCEL_GIT_COMMIT_REF"
 
 ## Do not automatically trigger build when pull-requesting into `deploy` branch.
-if [[ "$VERCEL_GIT_COMMIT_REF" == "candidate/"* ]] ; then
+if [[ "$VERCEL_GIT_COMMIT_REF" == "main" || "$VERCEL_GIT_COMMIT_REF" == "candidate/"* ]] ; then
   # Proceed with the build.
     echo "✅ - Preview build can proceed"
   exit 1;