Support multiple guards

[abdelhady-tk]

This pull request improves the guard resolution logic in the getAuth() method to support both single and multiple authentication guards as defined in the google2fa.guard configuration setting.

Previously, only a single guard could be used by specifying a string (e.g., 'web') in the config, and the code would directly call auth()->guard($guard). Now, the logic supports both a string or an array of guards (e.g., ['admin', 'agent']).

When multiple guards are provided, the method will loop through each guard and assign $this->auth to the first one that has an authenticated user (i.e., auth()->guard($guard)->check() returns true).

With this update, if a user is logged in under any of the specified guards, the package will automatically detect and use the correct guard. This greatly improves compatibility with multi-auth applications where users may belong to different guards such as admin, agent, or customer.

This change ensures that the correct authenticated context is selected without requiring developers to hard-code a specific guard or duplicate logic in their application.

Sample Issues Resolved by This Pull Request:
#103 , #90

[abdelhady-tk]

Hi @antonioribeiro,
I hope you're doing well. When you have a moment, would you mind reviewing this pull request? It adds support for multiple authentication guards and helps resolve issues #103 and #90.

Thank you in advance for your time and consideration