Get usage

curl --request GET \
  --url https://api.openwhispr.com/api/v1/usage \
  --header 'Authorization: Bearer <token>'

{
  "data": {
    "words_used": 123,
    "words_remaining": 123,
    "limit": 123,
    "plan": "free",
    "is_subscribed": true,
    "current_period_end": "2023-11-07T05:31:56Z",
    "billing_interval": "<string>"
  }
}