use instance axios, not global (#2846)

Author: vanvoljg

lib/helper/REST.js

@@ -59,7 +59,8 @@ class REST extends Helper {
 
     this.options = { ...this.options, ...config };
     this.headers = { ...this.options.defaultHeaders };
-    axios.defaults.headers = this.options.defaultHeaders;
+    this.axios = axios.create();
+    this.axios.defaults.headers = this.options.defaultHeaders;
   }
 
   static _checkRequirements() {
@@ -77,7 +78,7 @@ class REST extends Helper {
    */
   async _executeRequest(request) {
     const _debugRequest = { ...request };
-    axios.defaults.timeout = request.timeout || this.options.timeout;
+    this.axios.defaults.timeout = request.timeout || this.options.timeout;
 
     if (this.headers && this.headers.auth) {
       request.auth = this.headers.auth;
@@ -102,7 +103,7 @@ class REST extends Helper {
 
     let response;
     try {
-      response = await axios(request);
+      response = await this.axios(request);
     } catch (err) {
       if (!err.response) throw err;
       this.debugSection('Response', `Response error. Status code: ${err.response.status}`);