curl --request POST \
  --url http://localhost:8080/notifications/subscriptions \
  --header 'Content-Type: application/json' \
  --data '
{
  "event_type": "activation",
  "user_id": 2,
  "subscription_id": 2,
  "transaction_id": 2,
  "amount_kopeks": 1,
  "currency": "<string>",
  "message": "<string>",
  "occurred_at": "2023-11-07T05:31:56Z",
  "extra": {}
}
'

{
  "id": 123,
  "event_type": "<string>",
  "user_id": 123,
  "user_full_name": "<string>",
  "occurred_at": "2023-11-07T05:31:56Z",
  "created_at": "2023-11-07T05:31:56Z",
  "user_username": "<string>",
  "user_telegram_id": 123,
  "subscription_id": 123,
  "transaction_id": 123,
  "amount_kopeks": 123,
  "currency": "<string>",
  "message": "<string>",
  "extra": {}
}