[core] Match action with man repo

In case we start to use the next branch again.

.github/workflows/create-cherry-pick-pr.yml

@@ -2,6 +2,7 @@ name: Create cherry-pick PR
 on:
   pull_request_target:
     branches:
+      - 'next'
       - 'v*.x'
       - 'master'
     types: ['closed']