Sudan currency update

[kmuharam]

Hi,

In resources/currencies.php:719, the Sudanese currency has been update to SDG.

    'SDG' => [
        'name' => 'Sudanese Pound',
        'symbol' => 'SDG',
        'format' => '1,0.00 SDG,
        'exchange_rate' => 0.00,
    ],

Thanks for the great package 👍