enabled pm2 cluster

ecosystem.config.cjs

@@ -5,6 +5,8 @@ module.exports = {
     cwd: "/home/embruch/ragchat-api",
     node_args: "--env-file=./.env",
     watch: true,
+    instances: "4",
+    exec_mode: "cluster",
     ignore_watch: ["./node_modules", "./RAGFiles", "./.git", "./coverage", "./logs", "./__tests__"],
     error_file: 'logs/error.log',
     out_file: 'logs/output.log'