Refactored code to use PHP8 attributes instead of annotations

In this change, Doctrine and validation annotations have been replaced with PHP8 Attributes. The Rector tool has been configured with a list of annotations to convert to attributes. As a consequence, the PHPStan's rules have been updated to reflect these changes. The PHP8's nullable operator (?) has been added where required, and comments in field declaration have been replaced with #[Attribute] syntax.

src/Bundle/ChillPersonBundle/Entity/Relationships/Relationship.php

@@ -23,13 +23,11 @@ use Symfony\Component\Serializer\Annotation as Serializer;
 use Symfony\Component\Serializer\Annotation\DiscriminatorMap;
 use Symfony\Component\Validator\Constraints as Assert;
 
-/**
- * @RelationshipNoDuplicate
- */
 #[DiscriminatorMap(typeProperty: 'type', mapping: ['relationship' => Relationship::class])]
 #[ORM\Entity]
 #[DiscriminatorColumn(name: 'relation_id', type: 'integer')]
 #[ORM\Table(name: 'chill_person_relationships')]
+#[RelationshipNoDuplicate]
 class Relationship implements TrackCreationInterface, TrackUpdateInterface
 {
     #[ORM\Column(type: \Doctrine\DBAL\Types\Types::DATETIME_IMMUTABLE)]