Retrieves the balance of a specific relayer.

{
  "data": {
    "balance": 0,
    "unit": "wei"
  },
  "error": "string",
  "pagination": {
    "current_page": 0,
    "per_page": 0,
    "total_items": 0
  },
  "success": true
}

{
  "data": null,
  "message": "Bad Request",
  "success": false
}

{
  "data": null,
  "message": "Unauthorized",
  "success": false
}

{
  "data": null,
  "message": "Relayer with ID relayer_id not found",
  "success": false
}

{
  "data": null,
  "message": "Too Many Requests",
  "success": false
}

{
  "data": null,
  "message": "Internal Server Error",
  "success": false
}