Laravel 11 compatibility

[daniellesniak]

I updated some dependencies so it works with Laravel 11 now.

./vendor/bin/phpunit output:

PHPUnit 9.6.22 by Sebastian Bergmann and contributors.

Runtime:       PHP 8.3.11
Configuration: /home/daniel/code/laravel-mailgun-templates-channel/phpunit.xml

.....................................................             53 / 53 (100%)

Time: 00:00.245, Memory: 22.00 MB

OK (53 tests, 174 assertions)