fix: add void return type to Toolbar::prepare() for CI4.7 compatibility

[jozefrebjak]

Summary

Adds the void return type to Toolbar::prepare() method to maintain compatibility with CodeIgniter 4.7.0.

Changes

• Added : void return type to Toolbar::prepare() method in src/Debug/Toolbar.php

Reason

CodeIgniter 4.7.0 updated the base Toolbar class to require a void return type on the prepare() method. Without this change, the following fatal error occurs:

Declaration of Michalsn\CodeIgniterHtmx\Debug\Toolbar::prepare(?CodeIgniter\HTTP\RequestInterface $request = null, ?CodeIgniter\HTTP\ResponseInterface $response = null) must be compatible with CodeIgniter\Debug\Toolbar::prepare(?CodeIgniter\HTTP\RequestInterface $request = null, ?CodeIgniter\HTTP\ResponseInterface $response = null): void

Testing

• Verified that the method signature now matches the parent class
• No functional changes to the method implementation

[michalsn]

Thank you.