setTimeout needs to be defined in mail.d.ts

[huricool]

Issue Summary

The class MailService in mail.d.ts needs to define setTimeout in order to provide a proper type to the typescript compiler.

Steps to Reproduce

1. N/A

Code Snippet

  /**
   * Set timeout for request
   */
  setTimeout(timeout: number): void;

Exception/Log

Technical details:

• sendgrid-nodejs version: 6.5.4
• node version: NODE 12 LTS

[childish-sambino]

This issue has been added to our internal backlog to be prioritized. Pull requests and +1s on the issue summary will help it move up the backlog.