curl -X PUT "https://olive-gateway-a6ba.onrender.com/api/v1/subscribers/sub_abc123" \
  -H "Authorization: Bearer olive_live_xxx" \
  -H "Content-Type: application/json" \
  -d '{
    "email": "newemail@example.com"
  }'

{
  "success": true,
  "message": "Subscriber updated successfully",
  "subscriber": {
    "id": "sub_abc123",
    "phone_number": "+23279123456",
    "first_name": "John",
    "last_name": "Doe",
    "email": "newemail@example.com",
    "kyc_level": 2,
    "status": "ACTIVE",
    "updated_at": "2025-01-20T14:45:00Z"
  }
}