Validate entity's property value without unwanted dependancies - validation

Question

I have an "Customer" entity with several properties, one of them is "countryCode". When the country code gets set, it should be checked if it is valid. I could use the setter of Customer to do this validation but the problem is, there is a table "country" which holds the available country codes and as far as I know it is considered bad style to make an entity depended on any repositories.
I could let a service do the validation:
class CustomerUpdateService{
public function updateFromDto(Customer $customer, CustomerUpdateDto $updateDto): Customer
{
$countryCode = $updateDto->getCountryCode();
$country = $this->countryRepository->find($countryCode);
if (!isset($country){
throw new InvalidArgumentException('Unallowed country code ' . $countryCode);
}
$customer->setCountryCode($countryCode);
//update other properties
return $customer;
}
}
In my opion an entity should not allow to set invalid property states, so it has to to the validation by its own. But how to achieve this without generating unwanted dependencies? The only thing I can think of is passing the allowed countries to the setter:
class Customer{
public function setCountryCode(string $countryCode, array $availableCountries){
$availableCountryCodes = [];
foreach ($availableCountries as $country){
$availableCountryCodes[] = $country->getCode();
}
if (!in_array($countryCode, $availableCountryCodes)){
throw new InvalidArgumentException('Unallowed country code ' . $countryCode);
}
$this->countryCode = $countryCode;
}
}
Or passing a CountryCodeValidator to the setter:
class Customer{
public function setCountryCode(string $countryCode, CountryCodeValidator $validator){
$validator->validate($countryCode);
$this->countryCode = $countryCode;
}
}
Is this a legitimate solution? Are there better approaches?