Improve Typescript support

Author: vallpaper

lib/api-client.js

@@ -45,7 +45,7 @@ class ApiClient {
         url: url,
         headers: {'Accept': 'application/json',
                   'Content-Type': 'application/json',
-                  'User-Agent': 'recombee-node-api-client/4.1.1'},
+                  'User-Agent': 'recombee-node-api-client/4.1.2'},
         timeout: request.timeout,
         agent: this.options.agent
     };