Update SimpleCacheAdapter.php (#60)
Update SimpleCacheAdapter.php (#60)

When using `SimpleCacheAdapter` with the Laravel Redis cache adapter, the method `getIdWithHash` tries to return the string representation of the value in the store directly. Giving the following exception ```Symfony\Component\Debug\Exception\FatalThrowableError with message 'Return value of FlixTech\SchemaRegistryApi\Registry\Cache\SimpleCacheAdapter::getIdWithHash() must be of the type int or null, string returned'```

Co-authored-by: Thomas Ploch <8ec49d5a44b4a379ff92084ca4451b47ef901848@gmail.com>
flix-tech/schema-registry-php-client,flix-tech/schema-registry-php-client