Update filament-shield.php

[EGYWEB-Mohamed]

isRolePolicyRegistered does not accept an array

[what-the-diff]

PR Summary

• Change of register_role_policy format
  This update altered the system's settings related to role registration policy. Earlier, it would accept a list of options configured in the system (array format). Now, it has been streamlined to a simple true/false option (boolean format). This modification ultimately makes it easier for users to adjust this setting, enhancing usability and reducing complexity.

[bezhanSalleh]

Instead of adjusting the config, could you instead fix the method in the Utils.php instead. that way there won't be any breaking change for others to republish the config again and it will be just a fix.

[bezhanSalleh]

Since i'm doing a release and didn't hear from you i went ahead and brought the changes required myself.
Thanks for the fix.