Jayan Ratna

This PR changes the exception from `Exception` to `TransportException` to better identify the type of error that was caused.

This PR adds support for using your Resend API key through the `services.resend.key` config which was add in https://github.com/laravel/laravel/commit/4b1588713d05830f7cdf88159fa3739831d167cb. This PR also includes an updated PHP CS Fixer config file...

To improve the development experience it might be handy to create a fluent interface to easily send emails: ```php use Resend\Email; $resend = Resend::client('re_123456789'); $email = (new Email()) ->to('...') ->from('...')...

This PR changes the HTTP Transporter to check for JSON content-type when checking for error responses.