`vtupress_gateway_registry`
Add or remove payment gateways.
**Before:** Array containing `[‘paystack’ => ‘…’, ‘monnify’ => ‘…’]`
**Hook Example:**
```php
add_filter('vtupress_gateway_registry', function($registry) {
$registry['stripe'] = 'Stripe_Class';
return $registry;
});
```**After:** Array contains `[‘paystack’ => ‘…’, ‘monnify’ => ‘…’, ‘stripe’ => ‘Stripe_Class’]`