Remove is_plugin_check method from Abstract_Check_Runner Class

[mukeshpanchal27]

During the QA testing process for the repository hosted at #194 (comment), we have identified a specific error. The code in question involves the usage of abstract static functions in PHP, which is considered discouraged. It has come to our attention that the Check_Runner interface already declares this function, making its presence as an abstract method in Abstract_Check_Runner unnecessary.

As a result, we propose the removal of the aforementioned method from the Abstract_Check_Runner class to adhere to best practices and improve the codebase's maintainability and clarity.

CLI: Strict Standards: Static function WordPress\Plugin_Check\Checker\Abstract_Check_Runner::is_plugin_check() should not be abstract in /var/www/html/wp-content/plugins/plugin-check/includes/Checker/Abstract_Check_Runner.php on line 102

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.

[felixarntz]

Thanks @mukeshpanchal27!

[mukeshpanchal27]

@joemcgill or @swissspidy, could either of you review and approve this so that we can merge it when you have few moment please? Thank you!