Sync payment currencies with project config

[joshuabaker]

[joshuabaker]

Not fond of this workaround.

// Ensure that the payment currency is GBP
Event::on(
    Application::class,
    Application::EVENT_INIT,
    static function () {
        $paymentCurrencies = Commerce::getInstance()->getPaymentCurrencies();
        $primaryPaymentCurrency = $paymentCurrencies->getPrimaryPaymentCurrency();
        if ($primaryPaymentCurrency->iso !== 'GBP') {
            $primaryPaymentCurrency->iso = 'GBP';
            $paymentCurrencies->savePaymentCurrency($primaryPaymentCurrency);
        }
    }
);