fix alexa's request format

[dpanta94]

All Submissions:

• [x] Does your code follow the Extendables standards?
• [ ] Have you written new tests for your changes, as applicable?
• [x] Have you successfully run tests with your changes locally?

Changes proposed in this Pull Request:

How to test the changes in this Pull Request:

1. In sandobx mode you can in your code the below: do_action( 'woocommerce_amazon_pa_enable_alexa_notifications', 'ANYTHING_AS_TRACKING_NUMBER', 'VALID_AMAZON_CARRIER_CODE', (int) VALID_ORDER_ID_PAYED_WITH_AMAZON );

You can find a list of valid amazon carrier codes here

2. You should see an entry in the amazon log under woocommerce > status > logs about the result of the delivery notification
3. The alexa delivery notification request should return a 200 status response to be succesful

Other information:

• [x] Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changelog entry

FIX - Alexa delivery notification request format

[dpanta94]

Opened PR in woo repo, pull#243