Create UsageEvent

curl --request POST \
  --url https://app.flowglad.com/api/v1/usage-events \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '{
  "usageEvent": {
    "subscriptionId": "<string>",
    "amount": 1,
    "usageDate": 123,
    "transactionId": "<string>",
    "priceId": "<string>",
    "properties": {}
  }
}'

{
  "usageEvent": {
    "id": "<string>",
    "createdAt": "2023-11-07T05:31:56Z",
    "updatedAt": "2023-11-07T05:31:56Z",
    "createdByCommit": "<string>",
    "updatedByCommit": "<string>",
    "livemode": true,
    "customerId": "<string>",
    "subscriptionId": "<string>",
    "usageMeterId": "<string>",
    "billingPeriodId": "<string>",
    "amount": 1,
    "usageDate": "2023-11-07T05:31:56Z",
    "transactionId": "<string>",
    "priceId": "<string>",
    "properties": {}
  }
}