Initiate offramp

curl --request POST \
  --url https://api.privy.io/v1/users/{user_id}/fiat/offramp \
  --header 'Authorization: Basic <encoded-value>' \
  --header 'Content-Type: application/json' \
  --header 'privy-app-id: <privy-app-id>' \
  --data '{
  "amount": "<string>",
  "provider": "bridge",
  "source": {
    "currency": "usdc",
    "chain": "ethereum",
    "from_address": "<string>"
  },
  "destination": {
    "currency": "usd",
    "payment_rail": "sepa",
    "external_account_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
  }
}'

{
  "id": "<string>",
  "status": "awaiting_funds",
  "deposit_instructions": {
    "amount": "<string>",
    "currency": "usdc",
    "chain": "ethereum",
    "to_address": "<string>",
    "from_address": "<string>"
  }
}