Update proxy servers

curl --request PUT \
  --url https://cloud.volttime.com/api/v3/chargers/{charger_uuid}/proxy \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "vendor_role": "ROLE_FOLLOWER",
  "servers": null
}'

{
  "data": [
    {
      "websocket_url": "wss://tillman.com",
      "role": "follower",
      "created_at": "2025-07-04T13:42:21.000000Z",
      "updated_at": "2025-07-04T13:42:21.000000Z"
    },
    {
      "websocket_url": "wss://marquardt.com",
      "role": "follower",
      "created_at": "2025-07-04T13:42:21.000000Z",
      "updated_at": "2025-07-04T13:42:21.000000Z"
    }
  ]
}