Incorrect `use` statement with v4.0

[olinox14]

It seems the SerializerContextBuilderInterface was moved is the ApiPlatform\State namespace in v4, but the documentation still mentions the former one :

docs/core/serialization.md

Line 935 in 1cb130d

use ApiPlatform\Serializer\SerializerContextBuilderInterface;

[vinceAmstoutz]

Fixed in #2150