fix code lint

Author: qing-yang-20230331

lib/pool.js

@@ -56,7 +56,7 @@ class Pool extends EventEmitter {
         config: this.config.connectionConfig
       });
       this._allConnections.push(connection);
-      return connection.connect((err) => {
+      return connection.connect(err => {
         if (this._closed) {
           return cb(new Error('Pool is closed.'));
         }
@@ -101,7 +101,7 @@ class Pool extends EventEmitter {
   end(cb) {
     this._closed = true;
     if (typeof cb !== 'function') {
-      cb = function (err) {
+      cb = function(err) {
         if (err) {
           throw err;
         }
@@ -110,7 +110,7 @@ class Pool extends EventEmitter {
     let calledBack = false;
     let closedConnections = 0;
     let connection;
-    const endCB = function (err) {
+    const endCB = function(err) {
       if (calledBack) {
         return;
       }