Laravel 7+8 support

allow laravel 7+8

removed dev dependencies since tests are currently not maintained.

Forked from themsaid/laravel-langman

• support creating missing translation files
• Laravel 6 support
• PHP 7.3 support
• make it possible to generate a default text
• PSR-2 compliance
• make it possible to ignore certain keys
• make it possible to customize the function regexp
• make it possible to configure search paths