ci(github): use node 20.x in maintain-project workflow

Author: GitHub

.github/workflows/maintain-project.yml

@@ -4,7 +4,7 @@ on:
     - cron: 5 0 1 * *
   workflow_dispatch: null
 env:
-  NODE_VERSION: 19.x
+  NODE_VERSION: 20.x
 jobs:
   maintain-project:
     name: Maintain Project