Update README to reflect support for Node 22 LTS

[ejaxon]

Preflight Checklist

• I have read the Contributing Guidelines for this project.
• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a feature request that matches the one I want to file, without success.
• This is not a general Twilio feature request or bug report. It is a feature request for the twilio-node JavaScript package.

Problem Description

Official support for Node 22 was added by @manisha1997 on Dec 12, however the README still indicates support only through Node 20.

Proposed Solution

The change is simply to modify the Supported Node.js Versions section to add a "Node.js 20" line and modify the last line to be "Node.js LTS (22)".

Alternatives Considered

This is simply to catch the documentation up.

Additional Information

No response