Use the AnnotationReader interface in the SerializerBuilder, instead of the implemented AnnotationReader itself

When setting the annotation reader to the SerializerBuilder, the reader must be an instance of the *Doctrine\Common\Annotations\AnnotationReader* class. This disallows the possibility of using other annotation readers, such as the *CachedReader* of Doctrine or a custom implementation. A better solution would be to use the interface which describes the Annotation Reader: 

The set annotation reader is passed into the AnnotationDriver, which uses already the proper interface *Doctrine\Common\Annotations\Reader*