Use Kit WordPress Libraries 2.0.6

[n7studios]

Summary

Uses Kit WordPress Libraries 2.0.6, which includes support for the referrer parameter when subscribing to forms.

While the Kit for MemberMouse Plugin does not utilize the add_subscriber_to_form method, keeping the underlying libraries up-to-date is a good practice to ensure compatibility and maintain optimal functionality.

Testing

Existing tests pass.

Checklist

• I have written a test and included it in this PR
• I have run all tests and they pass
• The code passes when running the PHP CodeSniffer
• Code meets WordPress Coding Standards for PHP, HTML, CSS and JS
• Security and Sanitization requirements have been followed
• I have assigned a reviewer or two to review this PR (if you're not sure who to assign, we can do this step for you)