Syncing promotions is broken. enabled key value need to be boolean

[jlachancekffein]

This endpoint : ecommerce/stores/{store_id}/promo-rules
Params: enabled

Need to be boolean. This crash because craft\commerce\models\Discount->enabled return a string and Mailchimp API claims that the type should be a boolean.

Here my fix:
/src/craftCMS/vendor/ether/mailchimp-commerce/src/services/PromosService.php

private function _buildPromoData($promoId){
...
$data = [
            'id' => (string) $promo->id,
            'title' => $promo->name,
            'description' => $promo->description ?: $promo->name,
            'amount' => (float) $amount,
            'type' => $type,
            'target' => $target,
            'enabled' => filter_var($promo->enabled, FILTER_VALIDATE_BOOLEAN),
            'created_at_foreign' => $promo->dateCreated->format('c'),
            'updated_at_foreign' => $promo->dateUpdated->format('c'),
        ];
...
}

filter_var($promo->enabled, FILTER_VALIDATE_BOOLEAN)

[peteeveleigh]

Didn't see this here and have submitted a pull request with essentially the same fix
#41