Initiate a payment for a charging session
curl --request POST \ --url https://api.chargeapi.com/v1/payments/initiate \ --header 'Content-Type: application/json' \ --header 'X-API-Key: <api-key>' \ --data '{ "session_id": "<string>", "payment_method_id": "<string>", "amount": 123, "currency": "USD" }'