…ity checker

All Submissions:

• [x ] Have you followed the MainWP Contributing guideline?
• [x ] Does your code follow the WordPress' coding standards?
• [ x] Have you checked to ensure there aren't other open Pull Requests for the same update/change?

This update introduces Wordfence as an additional security option for the vulnerability scanning feature in the MainWP Child plugin. Wordfence is a widely trusted WordPress security plugin that provides real-time protection against vulnerabilities, malicious code, and threats.

By adding Wordfence to the MainWP Child vulnerability checker, users now have the flexibility to choose between different security tools based on their needs and existing configurations.